code: def zdecr(self, name, key, amount=1):
                                                  
          amount = get_positive_integer('amount', amount)
          return self.execute_command('zdecr', name, key, amount)
docs: Decrease the value of ``key`` in zset ``name`` by ``amount``. If no key
          exists, the value will be initialized as 0 - ``amount`` 
  
          :param string name: the zset name
          :param string key: the key name        
          :param int amount: increments
          :return: the integer value of ``key`` in zset ``name``
          :rtype: int
  
          >>> ssdb.zdecr('zset_2', 'key1', 7)
          36
          >>> ssdb.zdecr('zset_2', 'key2', 3)
          311
          >>> ssdb.zdecr('zset_2', 'key_not_exists', 101)
          -101
          >>> ssdb.zdecr('zset_not_exists', 'key_not_exists', 8848)
          -8848