in Source/TNLLRUCache.m [23:34]
NS_INLINE void TNLLRUCacheAssertHeadAndTail(TNLLRUCache *cache)
{
if (gTwitterNetworkLayerAssertEnabled) {
TNLAssert(!cache.headEntry == !cache.tailEntry);
if (cache.headEntry) {
TNLAssert(cache.cache[cache.headEntry.LRUEntryIdentifier] == cache.headEntry);
}
if (cache.tailEntry) {
TNLAssert(cache.cache[cache.tailEntry.LRUEntryIdentifier] == cache.tailEntry);
}
}
}