def is_atom(self):
        return isinstance(self.pred, AbstractVariableExpression)
Add only the required message, but no 'ng-required' attribute to the input fields,
dataset/ETHPy150Open nltk/nltk/nltk/sem/logic.py/ApplicationExpression.is_atom--crossover with--dataset/ETHPy150Open jrief/django-angular/djng/forms/field_mixins.py/MultipleFieldMixin.get_multiple_choices_required