Save
        Puts model into unit of work for persistence. Can optionally
        commit transaction. Returns persisted model as a result.

        :param model:           object, model to persist
        :param commit:          bool, commit transaction?
        :return:                object, saved model

def save(self, model, commit=True):
        """
        Save
        Puts model into unit of work for persistence. Can optionally
        commit transaction. Returns persisted model as a result.

        :param model:           object, model to persist
        :param commit:          bool, commit transaction?
        :return:                object, saved model
        """
        self.is_instance(model)
        db.session.add(model)
        if commit:
            db.session.commit()

        return model