                       `lch(0.7 45 none)`);
    test_valid_value(`color`, `lch(from lch(0.7 45 30) l c none / alpha)`,                                 `lch(0.7 45 none)`);
    test_valid_value(`color`, `lch(from lch(0.7 45 30) l c h / none)`,                                     `lch(0.7 45 30 / none)`);
    test_valid_value(`color`, `lch(from lch(0.7 45 30 / 40%) l c none / alpha)`,                           `lch(0.7 45 none / 0.4)`);
    test_valid_value(`color`, `lch(from lch(0.7 45 30 / 40%) l c h / none