def formfield(self, **kwargs):
        defaults = {'min_value': 1 - -BigIntegerField.MAX_BIGINT,
                    'max_value': BigIntegerField.MAX_BIGINT}
        defaults.update(kwargs)
        return super(BigIntegerField, self).formfield(**defaults)
dataset/ETHPy150Open AppScale/appscale/AppServer/lib/django-1.5/django/db/models/fields/__init__.py/BigIntegerField.formfield/swapped operands of `-`