def METHOD_NAME(empty_swagger_spec):
    array_of_array_spec = {
        'type': 'array',
        'items': {
            'type': 'array',
            'items': {
                'type': 'string',
            },
        },
    }
    input = [
        ['one'],
        ['two', 'three'],
        ['four', 'five', 'six'],
    ]
    expected = copy.deepcopy(input)
    result = unmarshal_array(empty_swagger_spec, array_of_array_spec, input)
    assert expected == result