An owning iterator over the entries of an LruCache.
This struct is created by the into_iter method on LruCache
(provided by the IntoIterator trait). See its documentation for more.
A least-recently-used (LRU) Cache with lazy eviction.
Each entry maintains an associated ordinal value representing when the
entry was last accessed. The cache is allowed to grow up to 2 times
specified capacity with no evictions, at which point, the excess entries
are evicted based on LRU policy resulting in an amortizedO(1)
performance.