OperationCallback<E extends Identifiable> typedef
OperationCallback<E extends Identifiable> =
Future<ManageOperation> Function(E updatedIdentifiable, List<E> list)
The returned ManageOperation determines whether the updatedIdentifiable
will be merged, removed or ignored from the list.
Implementation
typedef OperationCallback<E extends Identifiable> = Future<ManageOperation>
Function(E updatedIdentifiable, List<E> list);