Deskshell commands which take lists as arguments, for example list intersect and list count, use the list mark ``::'' to separate each argument.
list count a b c :: d e f ggives the result:
( 3 4 )
If the list mark ``::'' was not included, for example in the form:
list count $list1 $list2the result would be a single value, as the values of the two variables would combine to become a single list.