def create(self, validated_data):
        """Simple response object"""

        user = validated_data['user']
        result = {
            'balance': user.balance,
            'consumed': user.consumed,
            'result': 'authenticated',
        }
        return result

    def validate(self, data):
        """Check that username and password match an existing user"""

        user = authenticate(username=data.get('username'),
                            password=data.get('password'))
        if not user:
            raise ValidationError("Provided username and password don't match")

        elif not self.has_credit(user):
            raise ValidationError("Requested user has got no credit")

        else:
            data['user'] = user
            return data