grpc_invoke_arg_stack_with_attr_np - Executes an RPC.
  int grpc_invoke_arg_stack_with_attr_np(grpc_object_handle_t_np *handle,
                               char *method_name,
                               grpc_session_attr_t_np *session_attr,
                               grpc_arg_stack_t *stack)
  grpc_object_handle_t_np *handle  char *method_name  grpc_session_attr_t_np *session_attr  grpc_arg_stack_t *stackThis function is MT-safe.
  GRPC_NOT_INITIALIZED  GRPC_OTHER_ERROR_CODE