A pool of LRU caches.
var LRU =LRUPool =pool =c1 c2;c1 = pool;c1;c2 = pool;assert;
Options can be provided in the constructor
as well as when creating new caches via get
Refer to the lru-cache Options section of the readme for details.
pool.get(), for the first time a new cache will be created
and placed in a pool. Subsequent calls will get an existing cache from the
pool, unless it is expired; in which case a new cache will be created.