code: def ReplaceInFile(filename, old, new, encoding=None):
      '''
      Replaces all occurrences of "old" by "new" in the given file.
  
      :param unicode filename:
          The name of the file.
  
      :param unicode old:
          The string to search for.
  
      :param unicode new:
          Replacement string.
  
      :return unicode:
          The new contents of the file.
      '''
      contents = GetFileContents(filename, encoding=encoding)
      contents = contents.replace(old, new)
      CreateFile(filename, contents, encoding=encoding)
      return contentf ReplaceInFile(filename, old, new, encoding=None):
      '''
      Replaces all occurrences of "old" by "new" in the given file.
  
      :param unicode filename:
          The name of the file.
  
      :param unicode old:
          The string to search for.
  
      :param unicode new:
          Replacement string.
  
      :return unicode:
          The new contents of the file.
      '''
      contents = GetFileContents(filename, encoding=encoding)
      contents = contents.replace(old, new)
      CreateFile(filename, contents, encoding=encoding)
      return contents
docs: Replaces all occurrences of "old" by "new" in the given file.
  
      :param unicode filename:
          The name of the file.
  
      :param unicode old:
          The string to search for.
  
      :param unicode new:
          Replacement string.
  
      :return unicode:
          The new contents of the file.