Starts an automatic retriever that looks up statements and links related to things contained in the cache.

Call this method when the aggregator starts. Pulls the whitelisted aggregators for a starting-set of arguments, puts them into the cache and then spins up the automatic retriever.

Loop the next function with the queue until its empty.

Accepts a list and retrieves the statement the head-link is sourced by if its provider is whitelisted. Then retrieves all links connected to it and queues them. Returns the updated list.

Return whether the source of a link is whitelisted.