Checkpoints components

`BackwardCheckpointsView`

The BackwardCheckpointsView component renders a list of previous checkpoints that the underlying Store can go back to. Read more.

The CheckpointView component simply renders the label of a checkpoint. Read more.

The CurrentCheckpointView component renders the current checkpoint that the underlying Store is currently on. Read more.

The ForwardCheckpointsView component renders a list of future checkpoints that the underlying Store can go forwards to. Read more.