new_contents: class BucketList():
      def __init__(self, name, description):
          self.name = name
          self.description = description
          self.activities = []
          self.no_of_activities = len(self.activities)
  
      def add_activity(self, activity):
          self.activities.append(activity)
          return True
  
      def delete_activity(self, activity):
          pass
  
  class Activity():
      pass
  
  class User():
      def __init__(self, username, email, password):
          self.username = username
          self.email = email
          self.password = password
subject: Define the User class constructor