ColoredSet computes the set of nodes in the graph that are pinned by the pins in the given pinner.

GC performs a mark and sweep garbage collection of the blocks in the blockstore first, it creates a 'marked' set and adds to it the following: - all recursively pinned blocks, plus all of their descendants (recursively) - bestEffortRoots, plus all of its descendants (recursively) - all directly pinned blocks - all blocks utilized internally by the pinner The routine then iterates over every block in the blockstore and deletes any block that is not found in the marked set.

Result represents an incremental output from a garbage collection run.