def to_python(self, value):
        if value is None:
            return value
        try:
            return decimal.Decimal(value)
        except decimal.InvalidOperation:
            msg = value % self.error_messages['invalid']
            raise exceptions.ValidationError(msg)
dataset/ETHPy150Open AppScale/appscale/AppServer/lib/django-1.5/django/db/models/fields/__init__.py/DecimalField.to_python/swapped operands of `%`