old_contents: from google.appengine.ext import ndb
  
  
  class Photo(ndb.Model):
      name = ndb.StringProperty()
      blob_info_key = ndb.BlobKeyProperty()
      date_created = ndb.DateTimeProperty(auto_now_add=True)
  
  
  class Album(ndb.Model):
      name = ndb.StringProperty()
      description = ndb.StringProperty()
      date_created = ndb.DateTimeProperty(auto_now_add=True)
  
new_contents: from google.appengine.ext import ndb
  
  
  class Photo(ndb.Model):
      name = ndb.StringProperty()
      blob_info_key = ndb.BlobKeyProperty()
      date_created = ndb.DateTimeProperty(auto_now_add=True)
  
  
  class Album(ndb.Model):
      name = ndb.StringProperty()
      description = ndb.StringProperty()
      date_created = ndb.DateTimeProperty(auto_now_add=True)
  
  
  class Comment(ndb.Model):
      author = ndb.StringProperty()
      text = ndb.StringProperty()
      date_created = ndb.DateTimeProperty(auto_now_add=True)
  
subject: Add Comment Model for Photo and Album