private static Collection<PyClass> filterByImports(Collection<PyClass> classes, PsiFile containingFile) {
    if (classes.size() <= 1) {
      return classes;
    }
    List<PyClass> result = new ArrayList<>();
    for (PyClass pyClass : classes) {
      if (pyClass.getContainingFile() == containingFile) {
        result.add(pyClass);
      }
      else {
        final PsiElement exportedClass = ((PyFile)containingFile).getElementNamed(pyClass.getName());
        if (exportedClass == pyClass) {
          result.add(pyClass);
        }
      }
    }
    return result;
  }
private static Collection<PyClass> filterByImports(Collection<PyClass> classes, PsiFile containingFile)