def METHOD_NAME(*args, **kwargs):
    """Create a mock AppSession. Each mocked instance will have
    its own unique ID."""
    mock_id = mock.PropertyMock(
        return_value=f"mock_id:{ServerTestCase._next_session_id}"
    )
    ServerTestCase._next_session_id += 1
    mock_session = mock.MagicMock(AppSession, autospec=True, *args, **kwargs)
    type(mock_session).id = mock_id
    return mock_session