@Override
  public boolean isAvailable(@NotNull Project project,
                             @NotNull PsiFile file,
                             @NotNull PsiElement startElement,
                             @NotNull PsiElement endElement) {
    return super.isAvailable(project, file, startElement, endElement)
        && ((XPathFunctionCall)startElement).getArgumentList().length == 1;
    }
@Override
  public boolean isAvailable(@NotNull Project project,
                             @NotNull PsiFile file,
                             @NotNull PsiElement startElement,
                             @NotNull PsiElement endElement)