unsubscribe method
Implementation
bool unsubscribe(String topic) {
var ret = false;
if (_subscriptions.containsKey(topic)) {
var sub = _subscriptions[topic];
if (sub != null) {
ret = sub.remove(this);
if (sub.isEmpty) {
_subscriptions.remove(topic);
}
}
_localSubs.remove(topic);
}
return ret;
}