old_contents: from google.appengine.ext import ndb
  
  
  class Kid(ndb.Model):
      name = ndb.StringProperty()
      month = ndb.StringProperty()
      day = ndb.StringProperty()
      year = ndb.StringProperty()
new_contents: from google.appengine.ext import ndb
  
  
  class User(ndb.Model):
      email = ndb.StringProperty()
      groups = ndb.KeyProperty(kind='Group', repeated=True)
      
  class Group(ndb.Model):
      admins = ndb.KeyProperty(kind='User', repeated=True)
      members = ndb.KeyProperty(kind='User', repeated=True)
      name = ndb.StringProperty()
  
  class Chore(ndb.Model):
      name = ndb.StringProperty()
      due = ndb.DateTimeProperty()
      frequency = ndb.StringProperty()
      points = ndb.IntegerProperty()
      group_id = ndb.KeyProperty(kind='Group')
      assigned_to = ndb.KeyProperty(kind='User')
subject: Set up models