Dedupe converts a Subscription that may send duplicate Items into one that doesn't.

Fetch returns a Fetcher for Items from domain.

Merge returns a Subscription that merges the item streams from subs.

NaiveDedupe converts a stream of Items that may contain duplicates into one that doesn't.

Subscribe returns a new Subscription that uses fetcher to fetch Items.

FakeDuplicates causes the fake fetcher to return duplicate items.

An Item is a stripped-down RSS item.

A Fetcher fetches Items and returns the time when the next fetch should be attempted.

A Subscription delivers Items over a channel.