def METHOD_NAME(cache):
    with pytest.raises(KeyError):
        cache.get_mor('instance', 'mor_name')
    cache._mor['foo_instance'] = {'my_mor_name': {'foo': 'bar'}}
    assert cache.get_mor('foo_instance', 'my_mor_name')['foo'] == 'bar'
    with pytest.raises(MorNotFoundError):
        cache.get_mor('foo_instance', 'foo')