code: private void eliminateParamsAfter(Node fnNode, int argIndex) {
      Node formalArgPtr = NodeUtil.getFunctionParameters(fnNode).getFirstChild();
      while (argIndex != 0 && formalArgPtr != null) {
        formalArgPtr = formalArgPtr.getNext();
        argIndex--;
      }
      eliminateParamsAfter(fnNode, formalArgPtr);
    }
docs: Removes all formal parameters starting at argIndex.