docs: def from_urlsafe(cls, urlsafe):
          """
          Returns an instance of the model from a urlsafe string.
  
          :param urlsafe: urlsafe key
          :return: Instance of cls
          """
          try:
              key = ndb.Key(urlsafe=urlsafe)
          except:
              return None
          obj = key.get()
          if obj and isinstance(obj, cls):
              return obj