@Override
  public int getExpressionArgumentIndex(final GrExpression arg) {
    int res = 0;

    for (PsiElement cur = getFirstChild(); cur != null; cur = cur.getNextSibling()) {
      if (cur instanceof GrExpression) {
        if (arg == cur) return res;
        res++;
      }
    }

    return -1;
  }
@Override
  public int getExpressionArgumentIndex(final GrExpression arg)