removeValueListener method
Implementation
bool removeValueListener(ValueChanged<T> listener) {
if (!_valueListeners.containsKey(listener)) return false;
removeListener(_valueListeners.remove(listener)!);
return true;
}
bool removeValueListener(ValueChanged<T> listener) {
if (!_valueListeners.containsKey(listener)) return false;
removeListener(_valueListeners.remove(listener)!);
return true;
}