Add docs to `Mocker` so it's easier to understand.
Add docs to `Mocker` so it's easier to understand.

UnionOfRAD/lithium,wbeater/lithium,muyehub/lithium,m4rcsch/lithium-core-library,whowgames/lithium,pixelcog/lithium,datachand/lithium,davidpersson/lithium,jails/lithium,muyehub/lithium,pixelcog/lithium,mehlah/lithium,datachand/lithium,jails/lithium,davidpersson/lithium,graphis/lithium,SensCritique/lithium,whowgames/lithium,UnionOfRAD/lithium,wbeater/lithium,m4rcsch/lithium-core-library,mehlah/lithium,graphis/lithium,SensCritique/lithium