public async Task <Unit> Invoke(IStreamStore streamStore, CancellationToken ct)
{
var messageId = MessageId ?? (await streamStore.ReadStreamBackwards(
StreamId,
StreamVersion.GetValueOrDefault(-1),
1,
true,
ct))
.Messages.FirstOrDefault(
message => StreamVersion == Streams.StreamVersion.End ||
message.StreamVersion == StreamVersion)
.MessageId;
await streamStore.DeleteMessage(StreamId, messageId, ct);
return(Unit.Instance);
}