docs: def request(self, app_id=None, body=None, stamp=None, url=None, sig=None):
          """Validate application ID and request is from Alexa."""
          if self.app_id:
              if not self.application_id(app_id):
                  return False
  
          if (url or sig):
              if not (body and stamp and url and sig):
                  raise ValueError('Unable to validate sender, check arguments.')
              else:
                  if not self.sender(body, stamp, url, sig):
                      return False
  
          return True