code: def extract_payload(self):
          
          if not self.check_signature():
              raise InvalidSignature('Invalid Signature')
          if request.is_json:
              # Request.get_json() could be first called with silent=True.
              delete_cached_json_for(request)
              return request.get_json(silent=False, cache=False)
          elif request.content_type == 'application/x-www-form-urlencoded':
              return dict(request.form)
          raise InvalidPayload(request.content_type)
docs: Extract payload from request.