connect method
void
connect()
Implementation
void connect(String address, void Function(String) onConnected,
void Function() onDisconnected, void Function(String) onConnectionError) {
_connectCbMap[address] = onConnected;
_disconnectCbMap[address] = onDisconnected;
_connectErrorCbMap[address] = onConnectionError;
_channel.invokeMethod('connect', {"address": address});
}