@prefix list: <http://www.w3.org/2000/10/swap/list#>.
@prefix string: <http://www.w3.org/2000/10/swap/string#>.
@prefix seq: <https://eyereasoner.github.io/eye/reasoning/seq#>.

{
    (1 2 3 4 6 9 10 11 13) seq:punctuate ?A.
    ?A list:append ?B.
    (?C (", ")) list:append ?B.
    ?C string:concatenation ?D.
} => {
    (1 2 3 4 6 9 10 11 13) seq:answer ?D.
}.
