e(`color`, `rgb(from rebeccapurple r r r / r)`, `rgba(102, 102, 102, 0.4)`);
    test_valid_value(`color`, `rgb(from rebeccapurple alpha alpha alpha / alpha)`, `rgb(255, 255, 255)`);
    test_valid_value(`color`, `rgb(from rgb(20%, 40%, 60%, 80%) g b r)`, `rgb(102, 153, 51)`);
    test_valid_value(`color`, `rgb(from rgb(20%, 40%, 60%, 80%) b alpha r / g)`, `rgba(153, 204, 51, 0.4)`);
    test_valid_value(`color`, `rgb(from rgb(20%, 40%, 60%, 80%) r r r / r)`, `rgba(51, 51, 51, 0.2)`);
    test_valid_value(`