@Nullable
    private static PyClass getClassOwner(@Nullable PsiElement element) {
      for (ScopeOwner owner = ScopeUtil.getScopeOwner(element); owner != null; owner = ScopeUtil.getScopeOwner(owner)) {
        if (owner instanceof PyClass) {
          return (PyClass)owner;
        }
      }
      return null;
    }
@Nullable
    private static PyClass getClassOwner(@Nullable PsiElement element)