on method
Implementation
Function on(String channel, Function(dynamic) fn) {
_channels[channel] ??= ChalonaEvent(name: channel);
var r = _channels[channel]?.add(fn);
if (!ChalonaSocketIOChannel.isWSChannel(channel)) {
emit(ChalonaSocketIOChannel.channelSubscription.value,
{'channel': channel});
}
return r!;
}