post method
Implementation
Future<void> post(T payload) async
{
if(!_canWrite())
{
throw AssertionError('Cannot post to channel ${_channelId}, Channel was not published.');
}
final pkt =
DataPackage(sourceModule: _moduleId, channel: _channelId, unixTimestampMs: Int64(DateTime.now().millisecondsSinceEpoch));
_mutator.setter(pkt, payload);
await _manager.publish(pkt);
}