old_contents: # -*- encoding: utf-8 -*-
  from . import db
  
  
  class Activity(db.Model):
  
      item_id = db.Column(db.Integer, db.ForeignKey('item.id'), primary_key=True)
      time = db.Column(db.Integer, nullable=True)
      activity = db.Column(db.Integer, primary_key=True, autoincrement=False)
  
      @classmethod
      def get_activity_name(cls, activity):
          return cls.ACTIVITIES[activity]
  
      @classmethod
      def check_activity_existence(cls, activity):
          return activity in cls.ACTIVITIES
  
new_contents: # -*- encoding: utf-8 -*-
  from . import db
  
  
  class Activity(db.Model):
  
      item_id = db.Column(db.Integer, db.ForeignKey('item.id'), primary_key=True)
      time = db.Column(db.Integer, nullable=True)
      activity = db.Column(db.Integer, primary_key=True, autoincrement=False)
  
subject: remove unused methods