def _EncodeParameters(self, parameters):
    '''Return a string in key=value&key=value form

    Values of None are not included in the output string.

    Args:
      parameters:
        A dict of (key, value) tuples, where value is encoded as
        specified by self._encoding
    Returns:
      A URL-encoded string in "key=value&key=value" form
    '''
    if parameters is None:
      return None
    else:
      return urllib.urlencode(dict([(k, self._Encode(v)) for k, v in parameters.items() if v is not None]))
Return a string in key=value&key=value form

    Values of None are not included in the output string.

    Args:
      parameters:
        A dict of (key, value) tuples, where value is encoded as
        specified by self._encoding
    Returns:
      A URL-encoded string in "key=value&key=value" form
    
twitter/twitter.py