def METHOD_NAME():
    """
    https://github.com/online-ml/river/issues/1238
    >>> from river import compose
    >>> x = dict(a=0, b=1, x=2, y=3)
    >>> group_1 = compose.Select('a', 'b')
    >>> group_2 = compose.Select('x', 'y')
    >>> product = group_1 + group_2 + group_1 * group_2
    >>> sorted(product.transform_one(x), key=lambda k: (len(k), k))
    ['a', 'b', 'x', 'y', 'a*x', 'a*y', 'b*x', 'b*y']
    >>> product = group_1 * group_2 + group_1 + group_2
    >>> sorted(product.transform_one(x), key=lambda k: (len(k), k))
    ['a', 'b', 'x', 'y', 'a*x', 'a*y', 'b*x', 'b*y']
    >>> product = group_1 + group_1 * group_2
    >>> sorted(product.transform_one(x), key=lambda k: (len(k), k))
    ['a', 'b', 'a*x', 'a*y', 'b*x', 'b*y']
    """