void showNothingToRefactor() {
    CommonRefactoringUtil.showErrorHint(myProject, myEditor, PyBundle
                                          .message("refactoring.pull.up.error.cannot.perform.refactoring.no.base.classes",
                                                   myClassUnderRefactoring.getName()), RefactoringBundle.message("pull.members.up.title"),
                                        "members.pull.up"
    );
  }
void showNothingToRefactor()