text: class User:
      def __init__(self, first_name, last_name, user_name, password):
          self.first_name = first_name
          self.last_name = last_name
          self.user_name = user_name
          self.password = password
  
      user_User = []
  
      def keep_user(self):
  
          User.user_User.append(self)
  
      def delete_user(self):
  
          User.user_User.remove(self)
  
      @classmethod
      def display_users(cls):
  
          return cls.user_User
      @classmethod
      def find_by_name(cls, user_name):
          for user in cls.user_User:
              if user.user_name == user_name:
                  return user
  
      @classmethod
      def user_present(cls, user_name):
          for user in cls.user_User:
              if user.user_name == user_name:
                  return True
              return False
  
  
      
  
  