docs: def check_x_hub_signature(signature, message):
      """Check X-Hub-Signature used by GitHub to sign requests.
  
      :param signature: HMAC signature extracted from request.
      :param message: Request message.
      """
      hmac_value = get_hmac(message)
      if hmac_value == signature or \
         (signature.find('=') > -1 and
              hmac_value == signature[signature.find('=') + 1:]):
          return True
      return False