func fetcher(key interface{}) (interface{}, error) {
    res, err := db.GetDataByKey(key)
    return res, err
}

// Add cache to the cache manager
cachery.Add(cachery.NewDefault("some_cache", cachery.Config{
    // Time after cache become stale and should be updated from fetcher in background
    Expire: time.Second * 20,
    // Time after cache become outdated and should be updated immediately
    Lifetime: time.Second * 120,
    // Serializer is reusable.
    // There is JSON serializer as well, but it is slower and has some limitations like nanoseconds in time.Time.
    Serializer: &cachery.GobSerializer{},
    // Driver is reusable for different caches
    Driver:     inmemory.Default(),
    // Fetcher is function that fetch data from the underlying storage(e.g. database)
    // could be nil if you use fetcher parameter of Get function
    Fetcher:    fetcher,
    // Expvar will be used to populate cache statistics through expvar package
    // It could be nil if you don't need it
    Expvar: nil,
    // Tags allow you invalidate all caches in Manager which have specified tags
    // could be nil
    Tags: []string{"tag1", "tag2"},
}))

// Get cache from manager
c := cachery.Get("some_cache")
var val string

c.Get("some_key", &val, nil)
// Or override fetcher function from config
c.Get("some_key", &val, fetcher)

// Invalidate all keys
c.InvalidateAll()
// Invalidate single key
c.Invalidate("some_key")

//Invalidate all caches in manager
cachery.InvalidateAll()
//Invalidate caches in manager by tag
cachery.InvalidateTags("tag1")