Grpc::XS::Call
new(const char *class,  Grpc::XS::Channel channel,  \
    const char* method, Grpc::XS::Timeval deadline, ... )
  PREINIT:
    CallCTX* ctx = (CallCTX *)malloc( sizeof(CallCTX) );
    ctx->wrapped = NULL;
  CODE:
    ## some code removed ##
    ctx->wrapped = grpc_channel_create_call(
              channel->wrapped, NULL, GRPC_PROPAGATE_DEFAULTS,
              completion_queue, method, host_override, 
              deadline->wrapped, NULL);

    RETVAL = ctx;
  OUTPUT: RETVAL