text: """
  This module contains essential stuff that should've come with Python itself ;)
  
  It also contains functions (or functionality) which is in Python versions
  higher than 2.5 which used to be the lowest version supported by Scrapy.
  
  """
  import os
  import re
  import inspect
  import weakref
  import errno
  from functools import partial, wraps
  from sgmllib import SGMLParser
  
  
  class FixedSGMLParser(SGMLParser):
      """The SGMLParser that comes with Python has a bug in the convert_charref()
      method. This is the same class with the bug fixed"""
  
      def convert_charref(self, name):
          """This method fixes a bug in Python's SGMLParser."""
          try:
              n = int(name)
          except ValueError:
              return
          if not 0 <= n <= 127 : # ASCII ends at 127, not 255
              return
          return self.convert_codepoint(n)
  
  
  def flatten(x):
      """flatten(sequence) -> list
  
      Returns a single, flat list which contains all elements retrieved
      from the sequence and all recursively contained sub-sequences
      (iterables).
  
      Examples:
      >>> [1, 2, [3,4], (5,6)]
      [1, 2, [3, 4], (5, 6)]
      >>> flatten([[[1,2,3], (42,None)], [4,5], [6], 7, (8,9,10)])
      [1, 2, 3, 42, None, 4, 5, 6, 7, 8, 9, 10]"""
  
      result = []
      for el in x:
          if hasattr(el, "__iter__"):
              result.extend(flatten(el))
          else:
              result.append(el)
      return result
  
  
  def unique(list_, key=lambda x: x):
      """efficient function to uniquify a list preserving item order"""
      seen = set()
      result = []
      for item in list_:
          seenkey = key(item)
          if seenkey in seen:
              continue
          seen.add(seenkey)
          result.append(item)
      return result
  
  
  def str_to_unicode(text, encoding=None, errors='strict'):
      """Return the unicode representation of text in the given encoding. Unlike
      .encode(encoding) this function can be applied directly to a unicode
      object without the risk of double-decoding problems (which can happen if
      you don't use the default 'ascii' encoding)
      """
  
      if encoding is None:
          encoding = 'utf-8'
      if isinstance(text, str):
          return text.decode(encoding, errors)
      elif isinstance(text, unicode):
          return text
      else:
          raise TypeError('str_to_unicode must receive a str or unicode object, got %s' % type(text).__name__)
  
  def unicode_to_str(text, encoding=None, errors='strict'):
      """Return the str representation of text in the given encoding. Unlike
      .encode(encoding) this function can be applied directly to a str
      object without the risk of double-decoding problems (which can happen if
      you don't use the default 'ascii' encoding)
      """
  
      if encoding is None:
          encoding = 'utf-8'
      if isinstance(text, unicode):
          return text.encode(encoding, errors)
      elif isinstance(text, str):
          return text
      else:
          raise TypeError('unicode_to_str must receive a unicode or str object, got %s' % type(text).__name__)
  
  def re_rsearch(pattern, text, chunk_size=1024):
      """
      This function does a reverse search in a text using a regular expression
      given in the attribute 'pattern'.
      Since the re module does not provide this functionality, we have to find for
      the expression into chunks of text extracted from the end (for the sake of efficiency).
      At first, a chunk of 'chunk_size' kilobytes is extracted from the end, and searched for
      the pattern. If the pattern is not found, another chunk is extracted, and another
      search is performed.
      This process continues until a match is found, or until the whole file is read.
      In case the pattern wasn't found, None is returned, otherwise it returns a tuple containing
      the start position of the match, and the ending (regarding the entire text).
      """
      def _chunk_iter():
          offset = len(text)
          while True:
              offset -= (chunk_size * 1024)
              if offset <= 0:
                  break
              yield (text[offset:], offset)
          yield (text, 0)
  
      pattern = re.compile(pattern) if isinstance(pattern, basestring) else pattern
      for chunk, offset in _chunk_iter():
          matches = [match for match in pattern.finditer(chunk)]
          if matches:
              return (offset + matches[-1].span()[0], offset + matches[-1].span()[1])
      return None
  
  def memoizemethod_noargs(method):
      """Decorator to cache the result of a method (without arguments) using a
      weak reference to its object
      """
      cache = weakref.WeakKeyDictionary()
      @wraps(method)
      def new_method(self, *args, **kwargs):
          if self not in cache:
              cache[self] = method(self, *args, **kwargs)
          return cache[self]
      return new_method
  
  _BINARYCHARS = set(map(chr, range(32))) - set(["\0", "\t", "\n", "\r"])
  
  def isbinarytext(text):
      """Return True if the given text is considered binary, or false
      otherwise, by looking for binary bytes at their chars
      """
      assert isinstance(text, str), "text must be str, got '%s'" % type(text).__name__
      return any(c in _BINARYCHARS for c in text)
  
  def get_func_args(func, stripself=False):
      """Return the argument name list of a callable"""
      if inspect.isfunction(func):
          func_args, _, _, _ = inspect.getargspec(func)
      elif inspect.isclass(func):
          return get_func_args(func.__init__, True)
      elif inspect.ismethod(func):
          return get_func_args(func.__func__, True)
      elif inspect.ismethoddescriptor(func):
          return []
      elif isinstance(func, partial):
          return [x for x in get_func_args(func.func)[len(func.args):]
                  if not (func.keywords and x in func.keywords)]
      elif hasattr(func, '__call__'):
          if inspect.isroutine(func):
              return []
          else:
              return get_func_args(func.__call__, True)
      else:
          raise TypeError('%s is not callable' % type(func))
      if stripself:
          func_args.pop(0)
      return func_args
  
  def get_spec(func):
      """Returns (args, kwargs) tuple for a function
      >>> import re
      >>> get_spec(re.match)
      (['pattern', 'string'], {'flags': 0})
  
      >>> class Test(object):
      ...     def __call__(self, val):
      ...         pass
      ...     def method(self, val, flags=0):
      ...         pass
  
      >>> get_spec(Test)
      (['self', 'val'], {})
  
      >>> get_spec(Test.method)
      (['self', 'val'], {'flags': 0})
  
      >>> get_spec(Test().method)
      (['self', 'val'], {'flags': 0})
      """
  
      if inspect.isfunction(func) or inspect.ismethod(func):
          spec = inspect.getargspec(func)
      elif hasattr(func, '__call__'):
          spec = inspect.getargspec(func.__call__)
      else:
          raise TypeError('%s is not callable' % type(func))
  
      defaults = spec.defaults or []
  
      firstdefault = len(spec.args) - len(defaults)
      args = spec.args[:firstdefault]
      kwargs = dict(zip(spec.args[firstdefault:], defaults))
      return args, kwargs
  
  def equal_attributes(obj1, obj2, attributes):
      """Compare two objects attributes"""
      # not attributes given return False by default
      if not attributes:
          return False
  
      for attr in attributes:
          # support callables like itemgetter
          if callable(attr):
              if not attr(obj1) == attr(obj2):
                  return False
          else:
              # check that objects has attribute
              if not hasattr(obj1, attr):
                  return False
              if not hasattr(obj2, attr):
                  return False
              # compare object attributes
              if not getattr(obj1, attr) == getattr(obj2, attr):
                  return False
      # all attributes equal
      return True
  
  
  class WeakKeyCache(object):
  
      def __init__(self, default_factory):
          self.default_factory = default_factory
          self._weakdict = weakref.WeakKeyDictionary()
  
      def __getitem__(self, key):
          if key not in self._weakdict:
              self._weakdict[key] = self.default_factory(key)
          return self._weakdict[key]
  
  
  def stringify_dict(dct_or_tuples, encoding='utf-8', keys_only=True):
      """Return a (new) dict with the unicode keys (and values if, keys_only is
      False) of the given dict converted to strings. `dct_or_tuples` can be a
      dict or a list of tuples, like any dict constructor supports.
      """
      d = {}
      for k, v in dict(dct_or_tuples).iteritems():
          k = k.encode(encoding) if isinstance(k, unicode) else k
          if not keys_only:
              v = v.encode(encoding) if isinstance(v, unicode) else v
          d[k] = v
      return d
  
  def is_writable(path):
      """Return True if the given path can be written (if it exists) or created
      (if it doesn't exist)
      """
      if os.path.exists(path):
          return os.access(path, os.W_OK)
      else:
          return os.access(os.path.dirname(path), os.W_OK)
  
  def setattr_default(obj, name, value):
      """Set attribute value, but only if it's not already set. Similar to
      setdefault() for dicts.
      """
      if not hasattr(obj, name):
          setattr(obj, name, value)
  
  
  def retry_on_eintr(function, *args, **kw):
      """Run a function and retry it while getting EINTR errors"""
      while True:
          try:
              return function(*args, **kw)
          except IOError as e:
              if e.errno != errno.EINTR:
                  raise
  