def METHOD_NAME(app, users):
    """Test various ways to set the `removed_by` value for a tombstone."""
    user = users[0]
    # if the assigned value is an int or string, we assume it's a user ID
    t = Tombstone({})
    t.removed_by = user.id
    assert t.removed_by == {"user": str(user.id)}
    assert t.removed_by_proxy.resolve() == user
    # this comes in handy for setting the system to be the one who deleted the record
    t.removed_by = "system"
    assert t.removed_by == {"user": "system"}
    assert t.removed_by_proxy.resolve() == {
        "id": "system",
        "is_ghost": True,
        "profile": {"full_name": "System"},
        "username": "System",
    }
    # None should work as expected
    t.removed_by = None
    assert t.removed_by is None
    assert t.removed_by_proxy is None
    # setting a referenceable entity should use the `ResolverRegistry`
    t.removed_by = user
    assert ResolverRegistry.reference_entity(user) is not None
    assert t.removed_by == {"user": str(user.id)}
    assert t.removed_by_proxy.resolve() == user