AccumActionChange is similar to ActionChange except that it is also extendable.

ActionChange returns a Change that is based on the specified forward and reverse actions.

CombinedChange creates a composite change off of a number of smaller changes.

NewHistory creates a new History instance with the specified capacity, which determines the maximum amount of changes that will be tracked.

History tracks the sequence of changes and allows for undo and redo.

Change represents a state change.

ExtendableChange represents a change that can be extended (e.g.

Action represents a single unit for work.