#[global]
Instance Op_ltb : BinOp ltb :=
{| TBOp := Z.ltb; TBOpInj := ltb_lt |}.
Add Zify BinOp Op_ltb.

Lemma leb_le : forall n m,
(n <=? m)%sint63 = (to_Z n <=? to_Z m)%Z.