code: public void genArgs(List<JCExpression> trees, List<Type> pts) {
          for (List<JCExpression> l = trees; l.nonEmpty(); l = l.tail) {
              genExpr(l.head, pts.head).load();
              pts = pts.tail;
          }
          // require lists be of same length
          Assert.check(pts.isEmpty());
      }
docs: Derived visitor method: generate code for a list of method arguments.
  @param trees    The argument expressions to be visited.
  @param pts      The expression's expected types (i.e. the formal parameter
  types of the invoked method).