squareBrackets method args call message arguments at code split form M

squareBrackets := method(
  args := call message arguments at(0) code split;
  form := Message fromString(args at(0));
  name := args at(2);
  iterable := doString(args at(4));
  helper := Object clone;
  iterable foreach(elem, form doInContext(helper setSlot(name, elem)));
)