1	import Base
2	
3	# Says whether an open keeps its handle or rejects the requested options.
4	type Decision is Data:
5	  UseLocal{}
6	  UseRemote{}
7	  RejectOptions{}
8	
9	# Picks the handle kind that a matching open keeps.
10	def matched(local: Bool) -> Decision:
11	  match local:
12	    case True{}: UseLocal{}
13	    case False{}: UseRemote{}
14	
15	# Keeps the opened handle only when the requested options match the effective ones.
16	def choose(local: Bool, matches: Bool) -> Decision:
17	  match matches:
18	    case True{}: matched(local)
19	    case False{}: RejectOptions{}