def clean(self):
        seen_drinks = []

        for drink in self.cleaned_data:
            if drink['name'] in seen_drinks:
                raise ValidationError('You may only specify a drink once.')

            seen_drinks.append(drink['name'])
dataset/ETHPy150Open AppScale/appscale/AppServer/lib/django-1.3/tests/regressiontests/forms/tests/formsets.py/BaseFavoriteDrinksFormSet.clean/original