human
Solve the following python programming problem given the following code:
def invalidate_callable(callable, * args) : 
    "Invalidate the cache for a callable

    :param callable: The callable that was cached
    :type callable: callable object
    :param \\*args: Arguments the function was called with that
                   should be invalidated. If the args is just the
                   differentiator for the function, or not present, then all
                   values for the function will be invalidated.

    Example::

        @cache_region('short_term', 'small_engine')
        def local_search(search_term):
            # do search and return it

        @cache_region('long_term')
        def lookup_folks():
            # look them up and return them

        # To clear local_search for search_term = 'fred'
        invalidate_function(local_search, 'fred')

        # To clear all cached variations of the local_search function
        invalidate_function(local_search)

        # To clear out lookup_folks
        invalidate_function(lookup_folks)

    " 
    redis = global_connection.redis 
    region = callable._region 
    namespace = callable._namespace 
    new_created = ((time.time () - CacheRegion.regions [region] ['expires']) - 3600) 
    if args : 
        try : 
            cache_key = ' '.join (map (str, args)) 
except UnicodeEncodeError : 
            cache_key = ' '.join (map (unicode, args)) 
redis.hset (('retools:%s:%s:%s' % (region, namespace, cache_key)), 'created', new_created) 
else : 
        cache_keyset_key = ('retools:%s:%s:keys' % (region, cache_keyset_key)) 
        keys = (set (['']) | redis.smembers (cache_keyset_key)) 
        p = redis.pipeline (transaction = True) 
        for key in keys : 
            p.hset (('retools:%s:%s:%s' % (region, namespace, key)), 'created', new_created) 
p.execute () 
return None 

    
    

    Fix the buggy line: cache_keyset_key = ('retools:%s:%s:keys' % (region, cache_keyset_key))
assistant
#Here is Python code to fix the buggy line: cache_keyset_key = ('retools:%s:%s:keys' % (region, cache_keyset_key))
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cache_keyset_key = ('retools:%s:%s:keys' % (region, namespace))