func WithMemcache(client *memcache.Client) ConfFunc {
	return func(h *unfurlHandler) *unfurlHandler {
		if client != nil {
			h.Cache = client
		}
		return h
	}
}
WithMemcache configures unfurl handler to cache metadata in memcached
package unfurlist
import (
	"crypto/sha1"
	"net/http"
	"strings"
	"github.com/artyom/oembed"
	"github.com/bradfitz/gomemcache/memcache"
)
func WithHTTPClient(client *http.Client) ConfFunc {
	return func(h *unfurlHandler) *unfurlHandler {
		if client != nil {
			h.HTTPClient = client
		}
		return h
	}
}