fact: Definition twothree_add {V} (k : K) (v : V) (m : twothree V) : twothree V := twothree_modify k (fun _ => Some v) (Some v) m (fun m => m) Two.
imports: Coq.Lists.List ExtLib.Core.RelDec ExtLib.Structures.Maps ExtLib.Structures.Monads ExtLib.Structures.Reducible