urple 25 g b / alpha)`, `rgb(25, 51, 153)`);
    test_valid_value(`color`, `rgb(from rebeccapurple r 25 b / alpha)`, `rgb(102, 25, 153)`);
    test_valid_value(`color`, `rgb(from rebeccapurple r g 25 / alpha)`, `rgb(102, 51, 25)`);
    test_valid_value(`color`, `rgb(from rebeccapurple r g b / .25)`, `rgba(102, 51, 153, 0.25)`);
    test_valid_value(`color`, `rgb(from rgb(20%, 40%, 60%, 80%) 25 g b / alpha)`, `rgba(25, 102, 153, 0.8)`);
    test_valid_value(`color`, `rgb(from rgb(20%, 40%, 60%, 80%) r 25 b /