protected @Nullable PyExpression getInitializerForElement(@Nullable PsiElement element) {
    if (element == null) return null;
    final PsiElement parent = element.getParent();
    return parent instanceof PyAssignmentStatement ? ((PyAssignmentStatement)parent).getAssignedValue() :
           element instanceof PyExpression ? (PyExpression)element : null;
  }
protected @Nullable PyExpression getInitializerForElement(@Nullable PsiElement element)