def activate(token):
db = DB()
users = db.get_user_by_token(token)
if not users:
raise(UserNotFoundException() )
# constrain garantees that token is unique
user = users[0]
if not user[ACTIVATED] is None:
raise(UserAlreadyActivatedException() )
if user[CREATED] < str(datetime.datetime.now() - timedelta(days=settings.DAYS_TO_ACTIVATE)):
raise(UserExpiredException() )
db.activate_user(token)
return True
