text: //     Backbone.js 0.9.2
  
  //     (c) 2010-2012 Jeremy Ashkenas, DocumentCloud Inc.
  //     Backbone may be freely distributed under the MIT license.
  //     For all details and documentation:
  //     http://backbonejs.org
  
  (function(){
  
    // Initial Setup
    // -------------
  
    // Save a reference to the global object (`window` in the browser, `global`
    // on the server).
    var root = this;
  
    // Save the previous value of the `Backbone` variable, so that it can be
    // restored later on, if `noConflict` is used.
    var previousBackbone = root.Backbone;
  
    // Create a local reference to slice/splice.
    var slice = Array.prototype.slice;
    var splice = Array.prototype.splice;
  
    // The top-level namespace. All public Backbone classes and modules will
    // be attached to this. Exported for both CommonJS and the browser.
    var Backbone;
    if (typeof exports !== 'undefined') {
      Backbone = exports;
    } else {
      Backbone = root.Backbone = {};
    }
  
    // Current version of the library. Keep in sync with `package.json`.
    Backbone.VERSION = '0.9.2';
  
    // Require Underscore, if we're on the server, and it's not already present.
    var _ = root._;
    if (!_ && (typeof require !== 'undefined')) _ = require('underscore');
  
    // For Backbone's purposes, jQuery, Zepto, or Ender owns the `$` variable.
    var $ = root.jQuery || root.Zepto || root.ender;
  
    // Set the JavaScript library that will be used for DOM manipulation and
    // Ajax calls (a.k.a. the `$` variable). By default Backbone will use: jQuery,
    // Zepto, or Ender; but the `setDomLibrary()` method lets you inject an
    // alternate JavaScript library (or a mock library for testing your views
    // outside of a browser).
    Backbone.setDomLibrary = function(lib) {
      $ = lib;
    };
  
    // Runs Backbone.js in *noConflict* mode, returning the `Backbone` variable
    // to its previous owner. Returns a reference to this Backbone object.
    Backbone.noConflict = function() {
      root.Backbone = previousBackbone;
      return this;
    };
  
    // Turn on `emulateHTTP` to support legacy HTTP servers. Setting this option
    // will fake `"PUT"` and `"DELETE"` requests via the `_method` parameter and
    // set a `X-Http-Method-Override` header.
    Backbone.emulateHTTP = false;
  
    // Turn on `emulateJSON` to support legacy servers that can't deal with direct
    // `application/json` requests ... will encode the body as
    // `application/x-www-form-urlencoded` instead and will send the model in a
    // form param named `model`.
    Backbone.emulateJSON = false;
  
    // Backbone.Events
    // -----------------
  
    // Regular expression used to split event strings
    var eventSplitter = /\s+/;
  
    // A module that can be mixed in to *any object* in order to provide it with
    // custom events. You may bind with `on` or remove with `off` callback functions
    // to an event; trigger`-ing an event fires all callbacks in succession.
    //
    //     var object = {};
    //     _.extend(object, Backbone.Events);
    //     object.on('expand', function(){ alert('expanded'); });
    //     object.trigger('expand');
    //
    var Events = Backbone.Events = {
  
      // Bind one or more space separated events, `events`, to a `callback`
      // function. Passing `"all"` will bind the callback to all events fired.
      on: function(events, callback, context) {
  
        var calls, event, node, tail, list;
        if (!callback) return this;
        events = events.split(eventSplitter);
        calls = this._callbacks || (this._callbacks = {});
  
        // Create an immutable callback list, allowing traversal during
        // modification.  The tail is an empty object that will always be used
        // as the next node.
        while (event = events.shift()) {
          list = calls[event];
          node = list ? list.tail : {};
          node.next = tail = {};
          node.context = context;
          node.callback = callback;
          calls[event] = {tail: tail, next: list ? list.next : node};
        }
  
        return this;
      },
  
      // Remove one or many callbacks. If `context` is null, removes all callbacks
      // with that function. If `callback` is null, removes all callbacks for the
      // event. If `events` is null, removes all bound callbacks for all events.
      off: function(events, callback, context) {
        var event, calls, node, tail, cb, ctx;
  
        // No events, or removing *all* events.
        if (!(calls = this._callbacks)) return this;
        if (!(events || callback || context)) {
          delete this._callbacks;
          return this;
        }
  
        // Loop through the listed events and contexts, splicing them out of the
        // linked list of callbacks if appropriate.
        events = events ? events.split(eventSplitter) : _.keys(calls);
        while (event = events.shift()) {
          node = calls[event];
          delete calls[event];
          if (!node || !(callback || context)) continue;
          // Create a new list, omitting the indicated callbacks.
          tail = node.tail;
          while ((node = node.next) !== tail) {
            cb = node.callback;
            ctx = node.context;
            if ((callback && cb !== callback) || (context && ctx !== context)) {
              this.on(event, cb, ctx);
            }
          }
        }
  
        return this;
      },
  
      // Trigger one or many events, firing all bound callbacks. Callbacks are
      // passed the same arguments as `trigger` is, apart from the event name
      // (unless you're listening on `"all"`, which will cause your callback to
      // receive the true name of the event as the first argument).
      trigger: function(events) {
        var event, node, calls, tail, args, all, rest;
        if (!(calls = this._callbacks)) return this;
        all = calls.all;
        events = events.split(eventSplitter);
        rest = slice.call(arguments, 1);
  
        // For each event, walk through the linked list of callbacks twice,
        // first to trigger the event, then to trigger any `"all"` callbacks.
        while (event = events.shift()) {
          if (node = calls[event]) {
            tail = node.tail;
            while ((node = node.next) !== tail) {
              node.callback.apply(node.context || this, rest);
            }
          }
          if (node = all) {
            tail = node.tail;
            args = [event].concat(rest);
            while ((node = node.next) !== tail) {
              node.callback.apply(node.context || this, args);
            }
          }
        }
  
        return this;
      }
  
    };
  
    // Aliases for backwards compatibility.
    Events.bind   = Events.on;
    Events.unbind = Events.off;
  
    // Backbone.Model
    // --------------
  
    // Create a new model, with defined attributes. A client id (`cid`)
    // is automatically generated and assigned for you.
    var Model = Backbone.Model = function(attributes, options) {
      var defaults;
      attributes || (attributes = {});
      if (options && options.parse) attributes = this.parse(attributes);
      if (defaults = getValue(this, 'defaults')) {
        attributes = _.extend({}, defaults, attributes);
      }
      if (options && options.collection) this.collection = options.collection;
      this.attributes = {};
      this._escapedAttributes = {};
      this.cid = _.uniqueId('c');
      this.changed = {};
      this._silent = {};
      this._pending = {};
      this.set(attributes, {silent: true});
      // Reset change tracking.
      this.changed = {};
      this._silent = {};
      this._pending = {};
      this._previousAttributes = _.clone(this.attributes);
      this.initialize.apply(this, arguments);
    };
  
    // Attach all inheritable methods to the Model prototype.
    _.extend(Model.prototype, Events, {
  
      // A hash of attributes whose current and previous value differ.
      changed: null,
  
      // A hash of attributes that have silently changed since the last time
      // `change` was called.  Will become pending attributes on the next call.
      _silent: null,
  
      // A hash of attributes that have changed since the last `'change'` event
      // began.
      _pending: null,
  
      // The default name for the JSON `id` attribute is `"id"`. MongoDB and
      // CouchDB users may want to set this to `"_id"`.
      idAttribute: 'id',
  
      // Initialize is an empty function by default. Override it with your own
      // initialization logic.
      initialize: function(){},
  
      // Return a copy of the model's `attributes` object.
      toJSON: function(options) {
        return _.clone(this.attributes);
      },
  
      // Get the value of an attribute.
      get: function(attr) {
        return this.attributes[attr];
      },
  
      // Get the HTML-escaped value of an attribute.
      escape: function(attr) {
        var html;
        if (html = this._escapedAttributes[attr]) return html;
        var val = this.get(attr);
        return this._escapedAttributes[attr] = _.escape(val == null ? '' : '' + val);
      },
  
      // Returns `true` if the attribute contains a value that is not null
      // or undefined.
      has: function(attr) {
        return this.get(attr) != null;
      },
  
      // Set a hash of model attributes on the object, firing `"change"` unless
      // you choose to silence it.
      set: function(key, value, options) {
        var attrs, attr, val;
  
        // Handle both `"key", value` and `{key: value}` -style arguments.
        if (_.isObject(key) || key == null) {
          attrs = key;
          options = value;
        } else {
          attrs = {};
          attrs[key] = value;
        }
  
        // Extract attributes and options.
        options || (options = {});
        if (!attrs) return this;
        if (attrs instanceof Model) attrs = attrs.attributes;
        if (options.unset) for (attr in attrs) attrs[attr] = void 0;
  
        // Run validation.
        if (!this._validate(attrs, options)) return false;
  
        // Check for changes of `id`.
        if (this.idAttribute in attrs) this.id = attrs[this.idAttribute];
  
        var changes = options.changes = {};
        var now = this.attributes;
        var escaped = this._escapedAttributes;
        var prev = this._previousAttributes || {};
  
        // For each `set` attribute...
        for (attr in attrs) {
          val = attrs[attr];
  
          // If the new and current value differ, record the change.
          if (!_.isEqual(now[attr], val) || (options.unset && _.has(now, attr))) {
            delete escaped[attr];
            (options.silent ? this._silent : changes)[attr] = true;
          }
  
          // Update or delete the current value.
          options.unset ? delete now[attr] : now[attr] = val;
  
          // If the new and previous value differ, record the change.  If not,
          // then remove changes for this attribute.
          if (!_.isEqual(prev[attr], val) || (_.has(now, attr) != _.has(prev, attr))) {
            this.changed[attr] = val;
            if (!options.silent) this._pending[attr] = true;
          } else {
            delete this.changed[attr];
            delete this._pending[attr];
          }
        }
  
        // Fire the `"change"` events.
        if (!options.silent) this.change(options);
        return this;
      },
  
      // Remove an attribute from the model, firing `"change"` unless you choose
      // to silence it. `unset` is a noop if the attribute doesn't exist.
      unset: function(attr, options) {
        (options || (options = {})).unset = true;
        return this.set(attr, null, options);
      },
  
      // Clear all attributes on the model, firing `"change"` unless you choose
      // to silence it.
      clear: function(options) {
        (options || (options = {})).unset = true;
        return this.set(_.clone(this.attributes), options);
      },
  
      // Fetch the model from the server. If the server's representation of the
      // model differs from its current attributes, they will be overriden,
      // triggering a `"change"` event.
      fetch: function(options) {
        options = options ? _.clone(options) : {};
        var model = this;
        var success = options.success;
        options.success = function(resp, status, xhr) {
          if (!model.set(model.parse(resp, xhr), options)) return false;
          if (success) success(model, resp);
        };
        options.error = Backbone.wrapError(options.error, model, options);
        return (this.sync || Backbone.sync).call(this, 'read', this, options);
      },
  
      // Set a hash of model attributes, and sync the model to the server.
      // If the server returns an attributes hash that differs, the model's
      // state will be `set` again.
      save: function(key, value, options) {
        var attrs, current;
  
        // Handle both `("key", value)` and `({key: value})` -style calls.
        if (_.isObject(key) || key == null) {
          attrs = key;
          options = value;
        } else {
          attrs = {};
          attrs[key] = value;
        }
        options = options ? _.clone(options) : {};
  
        // If we're "wait"-ing to set changed attributes, validate early.
        if (options.wait) {
          if (!this._validate(attrs, options)) return false;
          current = _.clone(this.attributes);
        }
  
        // Regular saves `set` attributes before persisting to the server.
        var silentOptions = _.extend({}, options, {silent: true});
        if (attrs && !this.set(attrs, options.wait ? silentOptions : options)) {
          return false;
        }
  
        // After a successful server-side save, the client is (optionally)
        // updated with the server-side state.
        var model = this;
        var success = options.success;
        options.success = function(resp, status, xhr) {
          var serverAttrs = model.parse(resp, xhr);
          if (options.wait) {
            delete options.wait;
            serverAttrs = _.extend(attrs || {}, serverAttrs);
          }
          if (!model.set(serverAttrs, options)) return false;
          if (success) {
            success(model, resp);
          } else {
            model.trigger('sync', model, resp, options);
          }
        };
  
        // Finish configuring and sending the Ajax request.
        options.error = Backbone.wrapError(options.error, model, options);
        var method = this.isNew() ? 'create' : 'update';
        var xhr = (this.sync || Backbone.sync).call(this, method, this, options);
        if (options.wait) this.set(current, silentOptions);
        return xhr;
      },
  
      // Destroy this model on the server if it was already persisted.
      // Optimistically removes the model from its collection, if it has one.
      // If `wait: true` is passed, waits for the server to respond before removal.
      destroy: function(options) {
        options = options ? _.clone(options) : {};
        var model = this;
        var success = options.success;
  
        var triggerDestroy = function() {
          model.trigger('destroy', model, model.collection, options);
        };
  
        if (this.isNew()) {
          triggerDestroy();
          return false;
        }
  
        options.success = function(resp) {
          if (options.wait) triggerDestroy();
          if (success) {
            success(model, resp);
          } else {
            model.trigger('sync', model, resp, options);
          }
        };
  
        options.error = Backbone.wrapError(options.error, model, options);
        var xhr = (this.sync || Backbone.sync).call(this, 'delete', this, options);
        if (!options.wait) triggerDestroy();
        return xhr;
      },
  
      // Default URL for the model's representation on the server -- if you're
      // using Backbone's restful methods, override this to change the endpoint
      // that will be called.
      url: function() {
        var base = getValue(this, 'urlRoot') || getValue(this.collection, 'url') || urlError();
        if (this.isNew()) return base;
        return base + (base.charAt(base.length - 1) == '/' ? '' : '/') + encodeURIComponent(this.id);
      },
  
      // **parse** converts a response into the hash of attributes to be `set` on
      // the model. The default implementation is just to pass the response along.
      parse: function(resp, xhr) {
        return resp;
      },
  
      // Create a new model with identical attributes to this one.
      clone: function() {
        return new this.constructor(this.attributes);
      },
  
      // A model is new if it has never been saved to the server, and lacks an id.
      isNew: function() {
        return this.id == null;
      },
  
      // Call this method to manually fire a `"change"` event for this model and
      // a `"change:attribute"` event for each changed attribute.
      // Calling this will cause all objects observing the model to update.
      change: function(options) {
        options || (options = {});
        var changing = this._changing;
        this._changing = true;
  
        // Silent changes become pending changes.
        for (var attr in this._silent) this._pending[attr] = true;
  
        // Silent changes are triggered.
        var changes = _.extend({}, options.changes, this._silent);
        this._silent = {};
        for (var attr in changes) {
          this.trigger('change:' + attr, this, this.get(attr), options);
        }
        if (changing) return this;
  
        // Continue firing `"change"` events while there are pending changes.
        while (!_.isEmpty(this._pending)) {
          this._pending = {};
          this.trigger('change', this, options);
          // Pending and silent changes still remain.
          for (var attr in this.changed) {
            if (this._pending[attr] || this._silent[attr]) continue;
            delete this.changed[attr];
          }
          this._previousAttributes = _.clone(this.attributes);
        }
  
        this._changing = false;
        return this;
      },
  
      // Determine if the model has changed since the last `"change"` event.
      // If you specify an attribute name, determine if that attribute has changed.
      hasChanged: function(attr) {
        if (!arguments.length) return !_.isEmpty(this.changed);
        return _.has(this.changed, attr);
      },
  
      // Return an object containing all the attributes that have changed, or
      // false if there are no changed attributes. Useful for determining what
      // parts of a view need to be updated and/or what attributes need to be
      // persisted to the server. Unset attributes will be set to undefined.
      // You can also pass an attributes object to diff against the model,
      // determining if there *would be* a change.
      changedAttributes: function(diff) {
        if (!diff) return this.hasChanged() ? _.clone(this.changed) : false;
        var val, changed = false, old = this._previousAttributes;
        for (var attr in diff) {
          if (_.isEqual(old[attr], (val = diff[attr]))) continue;
          (changed || (changed = {}))[attr] = val;
        }
        return changed;
      },
  
      // Get the previous value of an attribute, recorded at the time the last
      // `"change"` event was fired.
      previous: function(attr) {
        if (!arguments.length || !this._previousAttributes) return null;
        return this._previousAttributes[attr];
      },
  
      // Get all of the attributes of the model at the time of the previous
      // `"change"` event.
      previousAttributes: function() {
        return _.clone(this._previousAttributes);
      },
  
      // Check if the model is currently in a valid state. It's only possible to
      // get into an *invalid* state if you're using silent changes.
      isValid: function() {
        return !this.validate || !this.validate(this.attributes);
      },
  
      // Run validation against the next complete set of model attributes,
      // returning `true` if all is well. If a specific `error` callback has
      // been passed, call that instead of firing the general `"error"` event.
      _validate: function(attrs, options) {
        if (options.silent || !this.validate) return true;
        attrs = _.extend({}, this.attributes, attrs);
        var error = this.validate(attrs, options);
        if (!error) return true;
        if (options && options.error) {
          options.error(this, error, options);
        } else {
          this.trigger('error', this, error, options);
        }
        return false;
      }
  
    });
  
    // Backbone.Collection
    // -------------------
  
    // Provides a standard collection class for our sets of models, ordered
    // or unordered. If a `comparator` is specified, the Collection will maintain
    // its models in sort order, as they're added and removed.
    var Collection = Backbone.Collection = function(models, options) {
      options || (options = {});
      if (options.model) this.model = options.model;
      if (options.comparator) this.comparator = options.comparator;
      this._reset();
      this.initialize.apply(this, arguments);
      if (models) this.reset(models, {silent: true, parse: options.parse});
    };
  
    // Define the Collection's inheritable methods.
    _.extend(Collection.prototype, Events, {
  
      // The default model for a collection is just a **Backbone.Model**.
      // This should be overridden in most cases.
      model: Model,
  
      // Initialize is an empty function by default. Override it with your own
      // initialization logic.
      initialize: function(){},
  
      // The JSON representation of a Collection is an array of the
      // models' attributes.
      toJSON: function(options) {
        return this.map(function(model){ return model.toJSON(options); });
      },
  
      // Add a model, or list of models to the set. Pass **silent** to avoid
      // firing the `add` event for every new model.
      add: function(models, options) {
        var i, index, length, model, cid, id, cids = {}, ids = {}, dups = [];
        options || (options = {});
        models = _.isArray(models) ? models.slice() : [models];
  
        // Begin by turning bare objects into model references, and preventing
        // invalid models or duplicate models from being added.
        for (i = 0, length = models.length; i < length; i++) {
          if (!(model = models[i] = this._prepareModel(models[i], options))) {
            throw new Error("Can't add an invalid model to a collection");
          }
          cid = model.cid;
          id = model.id;
          if (cids[cid] || this._byCid[cid] || ((id != null) && (ids[id] || this._byId[id]))) {
            dups.push(i);
            continue;
          }
          cids[cid] = ids[id] = model;
        }
  
        // Remove duplicates.
        i = dups.length;
        while (i--) {
          models.splice(dups[i], 1);
        }
  
        // Listen to added models' events, and index models for lookup by
        // `id` and by `cid`.
        for (i = 0, length = models.length; i < length; i++) {
          (model = models[i]).on('all', this._onModelEvent, this);
          this._byCid[model.cid] = model;
          if (model.id != null) this._byId[model.id] = model;
        }
  
        // Insert models into the collection, re-sorting if needed, and triggering
        // `add` events unless silenced.
        this.length += length;
        index = options.at != null ? options.at : this.models.length;
        splice.apply(this.models, [index, 0].concat(models));
        if (this.comparator && options.at == null) this.sort({silent: true});
        if (options.silent) return this;
        for (i = 0, length = this.models.length; i < length; i++) {
          if (!cids[(model = this.models[i]).cid]) continue;
          options.index = i;
          model.trigger('add', model, this, options);
        }
        return this;
      },
  
      // Remove a model, or a list of models from the set. Pass silent to avoid
      // firing the `remove` event for every model removed.
      remove: function(models, options) {
        var i, l, index, model;
        options || (options = {});
        models = _.isArray(models) ? models.slice() : [models];
        for (i = 0, l = models.length; i < l; i++) {
          model = this.getByCid(models[i]) || this.get(models[i]);
          if (!model) continue;
          delete this._byId[model.id];
          delete this._byCid[model.cid];
          index = this.indexOf(model);
          this.models.splice(index, 1);
          this.length--;
          if (!options.silent) {
            options.index = index;
            model.trigger('remove', model, this, options);
          }
          this._removeReference(model);
        }
        return this;
      },
  
      // Add a model to the end of the collection.
      push: function(model, options) {
        model = this._prepareModel(model, options);
        this.add(model, options);
        return model;
      },
  
      // Remove a model from the end of the collection.
      pop: function(options) {
        var model = this.at(this.length - 1);
        this.remove(model, options);
        return model;
      },
  
      // Add a model to the beginning of the collection.
      unshift: function(model, options) {
        model = this._prepareModel(model, options);
        this.add(model, _.extend({at: 0}, options));
        return model;
      },
  
      // Remove a model from the beginning of the collection.
      shift: function(options) {
        var model = this.at(0);
        this.remove(model, options);
        return model;
      },
  
      // Get a model from the set by id.
      get: function(id) {
        if (id == null) return void 0;
        return this._byId[id.id != null ? id.id : id];
      },
  
      // Get a model from the set by client id.
      getByCid: function(cid) {
        return cid && this._byCid[cid.cid || cid];
      },
  
      // Get the model at the given index.
      at: function(index) {
        return this.models[index];
      },
  
      // Return models with matching attributes. Useful for simple cases of `filter`.
      where: function(attrs) {
        if (_.isEmpty(attrs)) return [];
        return this.filter(function(model) {
          for (var key in attrs) {
            if (attrs[key] !== model.get(key)) return false;
          }
          return true;
        });
      },
  
      // Force the collection to re-sort itself. You don't need to call this under
      // normal circumstances, as the set will maintain sort order as each item
      // is added.
      sort: function(options) {
        options || (options = {});
        if (!this.comparator) throw new Error('Cannot sort a set without a comparator');
        var boundComparator = _.bind(this.comparator, this);
        if (this.comparator.length == 1) {
          this.models = this.sortBy(boundComparator);
        } else {
          this.models.sort(boundComparator);
        }
        if (!options.silent) this.trigger('reset', this, options);
        return this;
      },
  
      // Pluck an attribute from each model in the collection.
      pluck: function(attr) {
        return _.map(this.models, function(model){ return model.get(attr); });
      },
  
      // When you have more items than you want to add or remove individually,
      // you can reset the entire set with a new list of models, without firing
      // any `add` or `remove` events. Fires `reset` when finished.
      reset: function(models, options) {
        models  || (models = []);
        options || (options = {});
        for (var i = 0, l = this.models.length; i < l; i++) {
          this._removeReference(this.models[i]);
        }
        this._reset();
        this.add(models, _.extend({silent: true}, options));
        if (!options.silent) this.trigger('reset', this, options);
        return this;
      },
  
      // Fetch the default set of models for this collection, resetting the
      // collection when they arrive. If `add: true` is passed, appends the
      // models to the collection instead of resetting.
      fetch: function(options) {
        options = options ? _.clone(options) : {};
        if (options.parse === undefined) options.parse = true;
        var collection = this;
        var success = options.success;
        options.success = function(resp, status, xhr) {
          collection[options.add ? 'add' : 'reset'](collection.parse(resp, xhr), options);
          if (success) success(collection, resp);
        };
        options.error = Backbone.wrapError(options.error, collection, options);
        return (this.sync || Backbone.sync).call(this, 'read', this, options);
      },
  
      // Create a new instance of a model in this collection. Add the model to the
      // collection immediately, unless `wait: true` is passed, in which case we
      // wait for the server to agree.
      create: function(model, options) {
        var coll = this;
        options = options ? _.clone(options) : {};
        model = this._prepareModel(model, options);
        if (!model) return false;
        if (!options.wait) coll.add(model, options);
        var success = options.success;
        options.success = function(nextModel, resp, xhr) {
          if (options.wait) coll.add(nextModel, options);
          if (success) {
            success(nextModel, resp);
          } else {
            nextModel.trigger('sync', model, resp, options);
          }
        };
        model.save(null, options);
        return model;
      },
  
      // **parse** converts a response into a list of models to be added to the
      // collection. The default implementation is just to pass it through.
      parse: function(resp, xhr) {
        return resp;
      },
  
      // Proxy to _'s chain. Can't be proxied the same way the rest of the
      // underscore methods are proxied because it relies on the underscore
      // constructor.
      chain: function () {
        return _(this.models).chain();
      },
  
      // Reset all internal state. Called when the collection is reset.
      _reset: function(options) {
        this.length = 0;
        this.models = [];
        this._byId  = {};
        this._byCid = {};
      },
  
      // Prepare a model or hash of attributes to be added to this collection.
      _prepareModel: function(model, options) {
        options || (options = {});
        if (!(model instanceof Model)) {
          var attrs = model;
          options.collection = this;
          model = new this.model(attrs, options);
          if (!model._validate(model.attributes, options)) model = false;
        } else if (!model.collection) {
          model.collection = this;
        }
        return model;
      },
  
      // Internal method to remove a model's ties to a collection.
      _removeReference: function(model) {
        if (this == model.collection) {
          delete model.collection;
        }
        model.off('all', this._onModelEvent, this);
      },
  
      // Internal method called every time a model in the set fires an event.
      // Sets need to update their indexes when models change ids. All other
      // events simply proxy through. "add" and "remove" events that originate
      // in other collections are ignored.
      _onModelEvent: function(event, model, collection, options) {
        if ((event == 'add' || event == 'remove') && collection != this) return;
        if (event == 'destroy') {
          this.remove(model, options);
        }
        if (model && event === 'change:' + model.idAttribute) {
          delete this._byId[model.previous(model.idAttribute)];
          this._byId[model.id] = model;
        }
        this.trigger.apply(this, arguments);
      }
  
    });
  
    // Underscore methods that we want to implement on the Collection.
    var methods = ['forEach', 'each', 'map', 'reduce', 'reduceRight', 'find',
      'detect', 'filter', 'select', 'reject', 'every', 'all', 'some', 'any',
      'include', 'contains', 'invoke', 'max', 'min', 'sortBy', 'sortedIndex',
      'toArray', 'size', 'first', 'initial', 'rest', 'last', 'without', 'indexOf',
      'shuffle', 'lastIndexOf', 'isEmpty', 'groupBy'];
  
    // Mix in each Underscore method as a proxy to `Collection#models`.
    _.each(methods, function(method) {
      Collection.prototype[method] = function() {
        return _[method].apply(_, [this.models].concat(_.toArray(arguments)));
      };
    });
  
    // Backbone.Router
    // -------------------
  
    // Routers map faux-URLs to actions, and fire events when routes are
    // matched. Creating a new one sets its `routes` hash, if not set statically.
    var Router = Backbone.Router = function(options) {
      options || (options = {});
      if (options.routes) this.routes = options.routes;
      this._bindRoutes();
      this.initialize.apply(this, arguments);
    };
  
    // Cached regular expressions for matching named param parts and splatted
    // parts of route strings.
    var namedParam    = /:\w+/g;
    var splatParam    = /\*\w+/g;
    var escapeRegExp  = /[-[\]{}()+?.,\\^$|#\s]/g;
  
    // Set up all inheritable **Backbone.Router** properties and methods.
    _.extend(Router.prototype, Events, {
  
      // Initialize is an empty function by default. Override it with your own
      // initialization logic.
      initialize: function(){},
  
      // Manually bind a single named route to a callback. For example:
      //
      //     this.route('search/:query/p:num', 'search', function(query, num) {
      //       ...
      //     });
      //
      route: function(route, name, callback) {
        Backbone.history || (Backbone.history = new History);
        if (!_.isRegExp(route)) route = this._routeToRegExp(route);
        if (!callback) callback = this[name];
        Backbone.history.route(route, _.bind(function(fragment) {
          var args = this._extractParameters(route, fragment);
          callback && callback.apply(this, args);
          this.trigger.apply(this, ['route:' + name].concat(args));
          Backbone.history.trigger('route', this, name, args);
        }, this));
        return this;
      },
  
      // Simple proxy to `Backbone.history` to save a fragment into the history.
      navigate: function(fragment, options) {
        Backbone.history.navigate(fragment, options);
      },
  
      // Bind all defined routes to `Backbone.history`. We have to reverse the
      // order of the routes here to support behavior where the most general
      // routes can be defined at the bottom of the route map.
      _bindRoutes: function() {
        if (!this.routes) return;
        var routes = [];
        for (var route in this.routes) {
          routes.unshift([route, this.routes[route]]);
        }
        for (var i = 0, l = routes.length; i < l; i++) {
          this.route(routes[i][0], routes[i][1], this[routes[i][1]]);
        }
      },
  
      // Convert a route string into a regular expression, suitable for matching
      // against the current location hash.
      _routeToRegExp: function(route) {
        route = route.replace(escapeRegExp, '\\$&')
                     .replace(namedParam, '([^\/]+)')
                     .replace(splatParam, '(.*?)');
        return new RegExp('^' + route + '$');
      },
  
      // Given a route, and a URL fragment that it matches, return the array of
      // extracted parameters.
      _extractParameters: function(route, fragment) {
        return route.exec(fragment).slice(1);
      }
  
    });
  
    // Backbone.History
    // ----------------
  
    // Handles cross-browser history management, based on URL fragments. If the
    // browser does not support `onhashchange`, falls back to polling.
    var History = Backbone.History = function() {
      this.handlers = [];
      _.bindAll(this, 'checkUrl');
    };
  
    // Cached regex for cleaning leading hashes and slashes .
    var routeStripper = /^[#\/]/;
  
    // Cached regex for detecting MSIE.
    var isExplorer = /msie [\w.]+/;
  
    // Has the history handling already been started?
    History.started = false;
  
    // Set up all inheritable **Backbone.History** properties and methods.
    _.extend(History.prototype, Events, {
  
      // The default interval to poll for hash changes, if necessary, is
      // twenty times a second.
      interval: 50,
  
      // Gets the true hash value. Cannot use location.hash directly due to bug
      // in Firefox where location.hash will always be decoded.
      getHash: function(windowOverride) {
        var loc = windowOverride ? windowOverride.location : window.location;
        var match = loc.href.match(/#(.*)$/);
        return match ? match[1] : '';
      },
  
      // Get the cross-browser normalized URL fragment, either from the URL,
      // the hash, or the override.
      getFragment: function(fragment, forcePushState) {
        if (fragment == null) {
          if (this._hasPushState || forcePushState) {
            fragment = window.location.pathname;
            var search = window.location.search;
            if (search) fragment += search;
          } else {
            fragment = this.getHash();
          }
        }
        if (!fragment.indexOf(this.options.root)) fragment = fragment.substr(this.options.root.length);
        return fragment.replace(routeStripper, '');
      },
  
      // Start the hash change handling, returning `true` if the current URL matches
      // an existing route, and `false` otherwise.
      start: function(options) {
        if (History.started) throw new Error("Backbone.history has already been started");
        History.started = true;
  
        // Figure out the initial configuration. Do we need an iframe?
        // Is pushState desired ... is it available?
        this.options          = _.extend({}, {root: '/'}, this.options, options);
        this._wantsHashChange = this.options.hashChange !== false;
        this._wantsPushState  = !!this.options.pushState;
        this._hasPushState    = !!(this.options.pushState && window.history && window.history.pushState);
        var fragment          = this.getFragment();
        var docMode           = document.documentMode;
        var oldIE             = (isExplorer.exec(navigator.userAgent.toLowerCase()) && (!docMode || docMode <= 7));
  
        if (oldIE) {
          this.iframe = $('<iframe src="javascript:0" tabindex="-1" />').hide().appendTo('body')[0].contentWindow;
          this.navigate(fragment);
        }
  
        // Depending on whether we're using pushState or hashes, and whether
        // 'onhashchange' is supported, determine how we check the URL state.
        if (this._hasPushState) {
          $(window).bind('popstate', this.checkUrl);
        } else if (this._wantsHashChange && ('onhashchange' in window) && !oldIE) {
          $(window).bind('hashchange', this.checkUrl);
        } else if (this._wantsHashChange) {
          this._checkUrlInterval = setInterval(this.checkUrl, this.interval);
        }
  
        // Determine if we need to change the base url, for a pushState link
        // opened by a non-pushState browser.
        this.fragment = fragment;
        var loc = window.location;
        var atRoot  = loc.pathname == this.options.root;
  
        // If we've started off with a route from a `pushState`-enabled browser,
        // but we're currently in a browser that doesn't support it...
        if (this._wantsHashChange && this._wantsPushState && !this._hasPushState && !atRoot) {
          this.fragment = this.getFragment(null, true);
          window.location.replace(this.options.root + '#' + this.fragment);
          // Return immediately as browser will do redirect to new url
          return true;
  
        // Or if we've started out with a hash-based route, but we're currently
        // in a browser where it could be `pushState`-based instead...
        } else if (this._wantsPushState && this._hasPushState && atRoot && loc.hash) {
          this.fragment = this.getHash().replace(routeStripper, '');
          window.history.replaceState({}, document.title, loc.protocol + '//' + loc.host + this.options.root + this.fragment);
        }
  
        if (!this.options.silent) {
          return this.loadUrl();
        }
      },
  
      // Disable Backbone.history, perhaps temporarily. Not useful in a real app,
      // but possibly useful for unit testing Routers.
      stop: function() {
        $(window).unbind('popstate', this.checkUrl).unbind('hashchange', this.checkUrl);
        clearInterval(this._checkUrlInterval);
        History.started = false;
      },
  
      // Add a route to be tested when the fragment changes. Routes added later
      // may override previous routes.
      route: function(route, callback) {
        this.handlers.unshift({route: route, callback: callback});
      },
  
      // Checks the current URL to see if it has changed, and if it has,
      // calls `loadUrl`, normalizing across the hidden iframe.
      checkUrl: function(e) {
        var current = this.getFragment();
        if (current == this.fragment && this.iframe) current = this.getFragment(this.getHash(this.iframe));
        if (current == this.fragment) return false;
        if (this.iframe) this.navigate(current);
        this.loadUrl() || this.loadUrl(this.getHash());
      },
  
      // Attempt to load the current URL fragment. If a route succeeds with a
      // match, returns `true`. If no defined routes matches the fragment,
      // returns `false`.
      loadUrl: function(fragmentOverride) {
        var fragment = this.fragment = this.getFragment(fragmentOverride);
        var matched = _.any(this.handlers, function(handler) {
          if (handler.route.test(fragment)) {
            handler.callback(fragment);
            return true;
          }
        });
        return matched;
      },
  
      // Save a fragment into the hash history, or replace the URL state if the
      // 'replace' option is passed. You are responsible for properly URL-encoding
      // the fragment in advance.
      //
      // The options object can contain `trigger: true` if you wish to have the
      // route callback be fired (not usually desirable), or `replace: true`, if
      // you wish to modify the current URL without adding an entry to the history.
      navigate: function(fragment, options) {
        if (!History.started) return false;
        if (!options || options === true) options = {trigger: options};
        var frag = (fragment || '').replace(routeStripper, '');
        if (this.fragment == frag) return;
  
        // If pushState is available, we use it to set the fragment as a real URL.
        if (this._hasPushState) {
          if (frag.indexOf(this.options.root) != 0) frag = this.options.root + frag;
          this.fragment = frag;
          window.history[options.replace ? 'replaceState' : 'pushState']({}, document.title, frag);
  
        // If hash changes haven't been explicitly disabled, update the hash
        // fragment to store history.
        } else if (this._wantsHashChange) {
          this.fragment = frag;
          this._updateHash(window.location, frag, options.replace);
          if (this.iframe && (frag != this.getFragment(this.getHash(this.iframe)))) {
            // Opening and closing the iframe tricks IE7 and earlier to push a history entry on hash-tag change.
            // When replace is true, we don't want this.
            if(!options.replace) this.iframe.document.open().close();
            this._updateHash(this.iframe.location, frag, options.replace);
          }
  
        // If you've told us that you explicitly don't want fallback hashchange-
        // based history, then `navigate` becomes a page refresh.
        } else {
          window.location.assign(this.options.root + fragment);
        }
        if (options.trigger) this.loadUrl(fragment);
      },
  
      // Update the hash location, either replacing the current entry, or adding
      // a new one to the browser history.
      _updateHash: function(location, fragment, replace) {
        if (replace) {
          location.replace(location.toString().replace(/(javascript:|#).*$/, '') + '#' + fragment);
        } else {
          location.hash = fragment;
        }
      }
    });
  
    // Backbone.View
    // -------------
  
    // Creating a Backbone.View creates its initial element outside of the DOM,
    // if an existing element is not provided...
    var View = Backbone.View = function(options) {
      this.cid = _.uniqueId('view');
      this._configure(options || {});
      this._ensureElement();
      this.initialize.apply(this, arguments);
      this.delegateEvents();
    };
  
    // Cached regex to split keys for `delegate`.
    var delegateEventSplitter = /^(\S+)\s*(.*)$/;
  
    // List of view options to be merged as properties.
    var viewOptions = ['model', 'collection', 'el', 'id', 'attributes', 'className', 'tagName'];
  
    // Set up all inheritable **Backbone.View** properties and methods.
    _.extend(View.prototype, Events, {
  
      // The default `tagName` of a View's element is `"div"`.
      tagName: 'div',
  
      // jQuery delegate for element lookup, scoped to DOM elements within the
      // current view. This should be prefered to global lookups where possible.
      $: function(selector) {
        return this.$el.find(selector);
      },
  
      // Initialize is an empty function by default. Override it with your own
      // initialization logic.
      initialize: function(){},
  
      // **render** is the core function that your view should override, in order
      // to populate its element (`this.el`), with the appropriate HTML. The
      // convention is for **render** to always return `this`.
      render: function() {
        return this;
      },
  
      // Remove this view from the DOM. Note that the view isn't present in the
      // DOM by default, so calling this method may be a no-op.
      remove: function() {
        this.$el.remove();
        return this;
      },
  
      // For small amounts of DOM Elements, where a full-blown template isn't
      // needed, use **make** to manufacture elements, one at a time.
      //
      //     var el = this.make('li', {'class': 'row'}, this.model.escape('title'));
      //
      make: function(tagName, attributes, content) {
        var el = document.createElement(tagName);
        if (attributes) $(el).attr(attributes);
        if (content != null) $(el).html(content);
        return el;
      },
  
      // Change the view's element (`this.el` property), including event
      // re-delegation.
      setElement: function(element, delegate) {
        if (this.$el) this.undelegateEvents();
        this.$el = (element instanceof $) ? element : $(element);
        this.el = this.$el[0];
        if (delegate !== false) this.delegateEvents();
        return this;
      },
  
      // Set callbacks, where `this.events` is a hash of
      //
      // *{"event selector": "callback"}*
      //
      //     {
      //       'mousedown .title':  'edit',
      //       'click .button':     'save'
      //       'click .open':       function(e) { ... }
      //     }
      //
      // pairs. Callbacks will be bound to the view, with `this` set properly.
      // Uses event delegation for efficiency.
      // Omitting the selector binds the event to `this.el`.
      // This only works for delegate-able events: not `focus`, `blur`, and
      // not `change`, `submit`, and `reset` in Internet Explorer.
      delegateEvents: function(events) {
        if (!(events || (events = getValue(this, 'events')))) return;
        this.undelegateEvents();
        for (var key in events) {
          var method = events[key];
          if (!_.isFunction(method)) method = this[events[key]];
          if (!method) throw new Error('Method "' + events[key] + '" does not exist');
          var match = key.match(delegateEventSplitter);
          var eventName = match[1], selector = match[2];
          method = _.bind(method, this);
          eventName += '.delegateEvents' + this.cid;
          if (selector === '') {
            this.$el.bind(eventName, method);
          } else {
            this.$el.delegate(selector, eventName, method);
          }
        }
      },
  
      // Clears all callbacks previously bound to the view with `delegateEvents`.
      // You usually don't need to use this, but may wish to if you have multiple
      // Backbone views attached to the same DOM element.
      undelegateEvents: function() {
        this.$el.unbind('.delegateEvents' + this.cid);
      },
  
      // Performs the initial configuration of a View with a set of options.
      // Keys with special meaning *(model, collection, id, className)*, are
      // attached directly to the view.
      _configure: function(options) {
        if (this.options) options = _.extend({}, this.options, options);
        for (var i = 0, l = viewOptions.length; i < l; i++) {
          var attr = viewOptions[i];
          if (options[attr]) this[attr] = options[attr];
        }
        this.options = options;
      },
  
      // Ensure that the View has a DOM element to render into.
      // If `this.el` is a string, pass it through `$()`, take the first
      // matching element, and re-assign it to `el`. Otherwise, create
      // an element from the `id`, `className` and `tagName` properties.
      _ensureElement: function() {
        if (!this.el) {
          var attrs = _.extend({}, getValue(this, 'attributes'));
          if (this.id) attrs.id = this.id;
          if (this.className) attrs['class'] = this.className;
          this.setElement(this.make(this.tagName, attrs), false);
        } else {
          this.setElement(this.el, false);
        }
      }
  
    });
  
    // The self-propagating extend function that Backbone classes use.
    var extend = function (protoProps, classProps) {
      var child = inherits(this, protoProps, classProps);
      child.extend = this.extend;
      return child;
    };
  
    // Set up inheritance for the model, collection, and view.
    Model.extend = Collection.extend = Router.extend = View.extend = extend;
  
    // Backbone.sync
    // -------------
  
    // Map from CRUD to HTTP for our default `Backbone.sync` implementation.
    var methodMap = {
      'create': 'POST',
      'update': 'PUT',
      'delete': 'DELETE',
      'read':   'GET'
    };
  
    // Override this function to change the manner in which Backbone persists
    // models to the server. You will be passed the type of request, and the
    // model in question. By default, makes a RESTful Ajax request
    // to the model's `url()`. Some possible customizations could be:
    //
    // * Use `setTimeout` to batch rapid-fire updates into a single request.
    // * Send up the models as XML instead of JSON.
    // * Persist models via WebSockets instead of Ajax.
    //
    // Turn on `Backbone.emulateHTTP` in order to send `PUT` and `DELETE` requests
    // as `POST`, with a `_method` parameter containing the true HTTP method,
    // as well as all requests with the body as `application/x-www-form-urlencoded`
    // instead of `application/json` with the model in a param named `model`.
    // Useful when interfacing with server-side languages like **PHP** that make
    // it difficult to read the body of `PUT` requests.
    Backbone.sync = function(method, model, options) {
      var type = methodMap[method];
  
      // Default options, unless specified.
      options || (options = {});
  
      // Default JSON-request options.
      var params = {type: type, dataType: 'json'};
  
      // Ensure that we have a URL.
      if (!options.url) {
        params.url = getValue(model, 'url') || urlError();
      }
  
      // Ensure that we have the appropriate request data.
      if (!options.data && model && (method == 'create' || method == 'update')) {
        params.contentType = 'application/json';
        params.data = JSON.stringify(model);
      }
  
      // For older servers, emulate JSON by encoding the request into an HTML-form.
      if (Backbone.emulateJSON) {
        params.contentType = 'application/x-www-form-urlencoded';
        params.data = params.data ? {model: params.data} : {};
      }
  
      // For older servers, emulate HTTP by mimicking the HTTP method with `_method`
      // And an `X-HTTP-Method-Override` header.
      if (Backbone.emulateHTTP) {
        if (type === 'PUT' || type === 'DELETE') {
          if (Backbone.emulateJSON) params.data._method = type;
          params.type = 'POST';
          params.beforeSend = function(xhr) {
            xhr.setRequestHeader('X-HTTP-Method-Override', type);
          };
        }
      }
  
      // Don't process data on a non-GET request.
      if (params.type !== 'GET' && !Backbone.emulateJSON) {
        params.processData = false;
      }
  
      // Make the request, allowing the user to override any Ajax options.
      return $.ajax(_.extend(params, options));
    };
  
    // Wrap an optional error callback with a fallback error event.
    Backbone.wrapError = function(onError, originalModel, options) {
      return function(model, resp) {
        resp = model === originalModel ? resp : model;
        if (onError) {
          onError(originalModel, resp, options);
        } else {
          originalModel.trigger('error', originalModel, resp, options);
        }
      };
    };
  
    // Helpers
    // -------
  
    // Shared empty constructor function to aid in prototype-chain creation.
    var ctor = function(){};
  
    // Helper function to correctly set up the prototype chain, for subclasses.
    // Similar to `goog.inherits`, but uses a hash of prototype properties and
    // class properties to be extended.
    var inherits = function(parent, protoProps, staticProps) {
      var child;
  
      // The constructor function for the new subclass is either defined by you
      // (the "constructor" property in your `extend` definition), or defaulted
      // by us to simply call the parent's constructor.
      if (protoProps && protoProps.hasOwnProperty('constructor')) {
        child = protoProps.constructor;
      } else {
        child = function(){ parent.apply(this, arguments); };
      }
  
      // Inherit class (static) properties from parent.
      _.extend(child, parent);
  
      // Set the prototype chain to inherit from `parent`, without calling
      // `parent`'s constructor function.
      ctor.prototype = parent.prototype;
      child.prototype = new ctor();
  
      // Add prototype properties (instance properties) to the subclass,
      // if supplied.
      if (protoProps) _.extend(child.prototype, protoProps);
  
      // Add static properties to the constructor function, if supplied.
      if (staticProps) _.extend(child, staticProps);
  
      // Correctly set child's `prototype.constructor`.
      child.prototype.constructor = child;
  
      // Set a convenience property in case the parent's prototype is needed later.
      child.__super__ = parent.prototype;
  
      return child;
    };
  
    // Helper function to get a value from a Backbone object as a property
    // or as a function.
    var getValue = function(object, prop) {
      if (!(object && object[prop])) return null;
      return _.isFunction(object[prop]) ? object[prop]() : object[prop];
    };
  
    // Throw an error when a URL is needed, and none is supplied.
    var urlError = function() {
      throw new Error('A "url" property or function must be specified');
    };
  
  }).call(this);
  