I would like to remove from List a elements that are not in another List. Suppose I have

```
List a = [{"id": 1}, {"id": 2}, {"id": 4}, {"id": 7},]

List b = [{"id": 1}, {"id": 2}, {"id": 7},]

```

Then I would like to remove from List a the element `{"id": 4}`, since it is missing in List b

If List b were

```
List b = [{"id": 1}, {"id": 2}, {"id": 4},]

```

then I would like to remove from List a element `{"id": 7}`

How to do this in Flutter.

Thank you.