public boolean matchSequentially(PsiElement el1, PsiElement el2) {
    //if (el1==null || el2==null) return el1 == el2;
    return matchSequentially(new FilteringNodeIterator(SiblingNodeIterator.create(el1), getNodeFilter()),
                             new FilteringNodeIterator(SiblingNodeIterator.create(el2), getNodeFilter()));
  }
public boolean matchSequentially(PsiElement el1, PsiElement el2)