code: func (s *MemoryStore) changelistBetweenVersions(from, to api.Version) ([]api.Event, error) {
  	if s.proposer == nil {
  		return nil, errors.New("store does not support versioning")
  	}
  	changes, err := s.proposer.ChangesBetween(from, to)
  	if err != nil {
  		return nil, err
  	}
  
  	var changelist []api.Event
  
  	for _, change := range changes {
  		for _, sa := range change.StoreActions {
  			event, err := api.EventFromStoreAction(sa, nil)
  			if err != nil {
  				return nil, err
  			}
  			changelist = append(changelist, event)
  		}
  		changelist = append(changelist, state.EventCommit{Version: change.Version.Copy()})
  	}
  
  	return changelist, nil
  }
docs: // changelistBetweenVersions returns the changes after "from" up to and
  // including "to".