redis.zadd('language', 'C', 1)

Add an element to the sorted set and report an error ‘STR’ object has no attribute ‘items’

Error source

        for pair in iteritems(mapping):
            pieces.append(pair[1])
            pieces.append(pair[0])

We need a dictionary here

Modification

redis.zadd('language', {'C': 1})

Done!