contains<T> method
Checks if a type is registered (either as an instance or a factory)
Implementation
bool contains<T>({String? tag}) {
if (_disposed) {
return false;
}
final key = _makeKey<T>(tag);
// Check for existing instance
if (_instanceExists<T>(tag)) {
return true;
}
// Check for factory
return _factories.containsKey(key);
}