text: 'use strict';
  
  function Environment() {
  }
  
  Environment.prototype.extend = function (name, value) {
      var that = new Environment();
      that.name = name;
      that.value = value;
      that.parent = this;
      return that;
  };
  
  Environment.prototype.lookup = function (name) {
      if (typeof this.name === 'undefined') {
          return null;
      } else if (this.name === name) {
          return this.value;
      } else {
          return this.parent.lookup(name);
      }
  };
  
  // Exports
  
  module.exports = {
  	Environment: Environment,
  };
  