@spec noreply(
  state,
  opts :: [continue: continue, timeout: timeout()]
) :: {:noreply, state} | {:noreply, state, {:continue, continue} | timeout()}
when state: term(), continue: term()

@spec reply(state, result) :: {:reply, result, state}
when state: term(), result: term()

@spec reply(state, result, [{:continue, continue}]) ::
  {:reply, result, state, {:continue, continue}}
when state: term(), result: term(), continue: term()

@spec stop(state, reason) :: {:stop, reason, state} when state: term(), reason: term()