def login(cls, name, pw):
     u = cls.by_name(name)
     if u and HashManager.valid_pw(name, pw, u.pw_hash):
         return u
 def register(cls, name, pw, email=None):
     pw_hash = HashManager.make_pw_hash(name, pw)
     return User(parent=users_key(), name=name, pw_hash=pw_hash, email=email)