PollVoteChanged<T extends Object> typedef
Called when the user casts, changes, or clears (null) their vote.
The returned future is awaited before the "submitting" state clears, so a
host app can await a network call before SimplePoll reflects the vote.
Implementation
typedef PollVoteChanged<T extends Object> = FutureOr<void> Function(
PollVote<T>? vote,
);