code: def ltrim(self, key, start, stop):
          
          redis_list = self._get_list(key, 'LTRIM')
          if redis_list:
              start, stop = self._translate_range(len(redis_list), start, stop)
              self.redis[self._encode(key)] = redis_list[start:stop + 1]
          return True
docs: Emulate ltrim.