def pick_upper
import stelliferous@0.0.2.0/proofs/nat_extrema.bend as NatExtremaimport Base
62def pick_upper(choice: Bool,+left: Nat,+right: Nat,+upper: Nat,left_ok: {Nat.is_le(left,upper) == True{} : Bool},right_ok: {Nat.is_le(right,upper) == True{} : Bool}) ->
63 {Nat.is_le(Bool.pick(Nat,choice,left,right),upper) == True{} : Bool}:
64 match choice:
65 case False{}: right_ok
66 case True{}: left_ok