code: public <T extends JCTree> List<T> translate(List<T> trees, Type pt) {
          Type prevPt = this.pt;
          List<T> res;
          try {
              this.pt = pt;
              res = translate(trees);
          } finally {
              this.pt = prevPt;
          }
          return res;
      }
docs: Visitor method: perform a type translation on list of trees.