code: def execute_service_endpoint_request(self, service_endpoint_request, project, endpoint_id):
          
          route_values = {}
          if project is not None:
              route_values['project'] = self._serialize.url('project', project, 'str')
          query_parameters = {}
          if endpoint_id is not None:
              query_parameters['endpointId'] = self._serialize.query('endpoint_id', endpoint_id, 'str')
          content = self._serialize.body(service_endpoint_request, 'ServiceEndpointRequest')
          response = self._send(http_method='POST',
                                location_id='cc63bb57-2a5f-4a7a-b79c-c142d308657e',
                                version='5.0-preview.1',
                                route_values=route_values,
                                query_parameters=query_parameters,
                                content=content)
          return self._deserialize('ServiceEndpointRequestResult', response)
docs: ExecuteServiceEndpointRequest.
          [Preview API] Proxy for a GET request defined by a service endpoint.
          :param :class:`<ServiceEndpointRequest> <azure.devops.v5_0.service_endpoint.models.ServiceEndpointRequest>` service_endpoint_request: Service endpoint request.
          :param str project: Project ID or project name
          :param str endpoint_id: Id of the service endpoint.
          :rtype: :class:`<ServiceEndpointRequestResult> <azure.devops.v5_0.service_endpoint.models.ServiceEndpointRequestResult>`