Method remove

include/proj/internal/lru_cache.hpp:180–189

     */
    Value getCopy(const Key &key) { return get(key); }
    bool remove(const Key &key) {
        Guard g(lock_);
        auto iter = cache_.find(key);
        if (iter == cache_.end()) {
            return false;
        }
        keys_.erase(iter->second);
        cache_.erase(iter);
        return true;
    }
    bool contains(const Key &key) {
        Guard g(lock_);
        return cache_.find(key) != cache_.end();