@Nullable
  private static String elementName(PsiElement element) {
    if (element instanceof PyImportElement) {
      return ((PyImportElement) element).getVisibleName();
    }
    if (element instanceof PyReferenceExpression || element instanceof PyTargetExpression) {
      final QualifiedName qname = ((PyQualifiedExpression)element).asQualifiedName();
      if (qname != null) {
        return qname.toString();
      }
    }
    return element instanceof PyElement ? ((PyElement)element).getName() : null;
  }
@Nullable
  private static String elementName(PsiElement element)