def String.join
import Base2188def String.join(xs: List<&2, String>, +sep: String) -> String:
2189 match xs:
2190 case Nil{}:
2191 SNil{}
2192 case h <> t:
2193 String.join.go(t, h, sep)
import Base2188def String.join(xs: List<&2, String>, +sep: String) -> String:
2189 match xs:
2190 case Nil{}:
2191 SNil{}
2192 case h <> t:
2193 String.join.go(t, h, sep)