append

append($list, $val, $separator:auto)

Appends a single value onto the end of a list.

Unless the $separator argument is passed, if the list had only one item, the resulting list will be space-separated.

Like all list functions, append() returns a new list rather than modifying its argument in place.

append(10px 20px, 30px) => 10px 20px 30px
append((blue, red), green) => blue, red, green
append(10px 20px, 30px 40px) => 10px 20px (30px 40px)
append(10px, 20px, comma) => 10px, 20px
append((blue, red), green, space) => blue red green