@staticmethod
def get_message_from_response(r):
    """
        composes the error message using information eventually present
        in the response (http error code and the http response body)

        :param r: response object
        :return: string with error message or None if it fails
        """
    try:
        message = '[*] Error {0}: {1}'.format(r.status_code, r.text)
    except Exception:
        message = None
    return message
