1	import Base
2	import ./world.bend as W
3	import ./lifecycle.bend as Life
4	
5	type Tag is Data:Tag{}
6	type Record<S:Data,P:Type> is Type:
7	  Record{handle:W.Handle<S>,stamp:Life.Stamp,payload:Maybe<P>}
8	type Replacement<World:Type,S:Data,P:Type> is Type:
9	  Applied{world:World,previous:Record<S,P>}
10	  Refused{world:World,incoming:Maybe<P>,error:W.WorldError}