Do I _have to_ send a message before reading for user input?

bot.command('round').keyboard(...).answer(function (ctx) {
  ...
});

doesn't work.

Is it possible to have this enabled? I don't necessarily have to send a message before every a command. Specifically, when redirecting with ctx.go(), it isn't always necessary in my use case.

---

Already tried

bot.command('round').keyboard(...)
.invoke(function (ctx) {
  return Promise.resolve(ctx);
}).
.answer(function (ctx) {
  ...
});

doesn't seem to work either.