code: public final void nameArgument(String name, int index)
      {
          VariableElement lv = getLocalVariable(index);
          if (lv instanceof UpdateableElement)
          {
              UpdateableElement ue = (UpdateableElement) lv;
              ue.setSimpleName(El.getName(name));
          }
          else
          {
              throw new IllegalArgumentException("local variable at index "+index+" cannot be named");
          }
      }
docs: Names an argument
  @param name Argument name
  @param index First argument is 1, this = 0