text: from argon2 import PasswordHasher
  from models.user import UserModel
  
  ph = PasswordHasher()
  
  def authenticate(username, password):
      user = UserModel.find_by_username(username)
      if user and ph.verify(user.password, password):
          return user
  
  
  def identity(payload):
      user_id = payload['identity']
      return UserModel.find_by_id(user_id)