Internal: encode a string for url representation

def encode(cls, d):
        """
        Internal: encode a string for url representation
        """
        warnings.warn(
            'The `encode` class method of APIRequestor is deprecated and '
            'will be removed in version 2.0.'
            'If you need public access to this function, please email us '
            'at support@stripe.com.',
            DeprecationWarning)
        return urllib.urlencode(list(_api_encode(d)))