NewHeadBroadcaster creates a new HeadBroadcaster.

NewHeadListener creates a new HeadListener.

NewHeadTracker instantiates a new HeadTracker using HeadSaver to persist new block numbers.

HeadsBufferSize - The buffer is used when heads sampling is disabled, to ensure the callback is run for every head.

Config represents a subset of options needed by head tracker.

Heads is a collection of heads.