docs: def save(self, user, commit=True):
          """ Persist user and emit event """
          self.is_instance(user)
  
          schema = UpdateSchema()
          valid = schema.process(user)
          if not valid:
              return valid
  
          db.session.add(user)
          if commit:
              db.session.commit()
  
          events.user_save_event.send(user)
          return user