A[] = 1 2 3

A.foreach(a)
   A.foreach(aa)
      value $(aa)$(aa)
   eprintln($"a: $a")

M. =
   extends $(Map)
   $|1| = 1
   $|2| = 2
   $|3| = 3

M.foreach(k, v)
   M.foreach(kk, vv)
      value $(vv)$(vv)
   eprintln($"k: $k; v: $v")
