The cache mechanism:

• should be a promise
• should be replaceable with any other module*
• should have something hook-like to allow storing different properties e.g. ip addresses
• should accept different caching logic
• should make a new request when the cached response cannot be updated (#963)
• beforeCache hook

* Through the request option. Accepting ClientRequest and IncomingMessage as the return type. Return undefined to fallback. You can override the request option also by returning a ClientRequest or an IncomingMessage instance in a beforeRequest hook.