Retrieves the raw XML (decrypted) of the last SAML response,
        or the last Logout Response generated or processed
        :returns: SAML response XML
        :rtype: string|None

def get_last_response_xml(self, pretty_print_if_possible=False):
        """
        Retrieves the raw XML (decrypted) of the last SAML response,
        or the last Logout Response generated or processed
        :returns: SAML response XML
        :rtype: string|None
        """
        response = None
        if self.__last_response is not None:
            if isinstance(self.__last_response, compat.str_type):
                response = self.__last_response
            else:
                response = tostring(self.__last_response, encoding='unicode', pretty_print=pretty_print_if_possible)
        return response