@Override
    public void invoke(@NotNull Project project, Editor editor, PsiFile file) throws IncorrectOperationException {
        final XmlAttribute attribute = PsiTreeUtil.getContextOfType(myToken, XmlAttribute.class, true);
        assert attribute != null;

        final PsiFile f = XPathChangeUtil.createXPathFile(myToken,
                getOperandText(myExpression.getROperand()) + " " +
                        myToken.getText().replace('<', '>') + " " +
                        getOperandText(myExpression.getLOperand())
        );

        final PsiElement firstChild = f.getFirstChild();
        assert firstChild != null;

        myExpression.replace(firstChild);
    }
@Override
    public void invoke(@NotNull Project project, Editor editor, PsiFile file)