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

(* Specifications: *)
Lemma leb_le : forall n m, (n <=? m)%uint63 = (φ (n)%uint63 <=? φ (m)%uint63)%Z.
Lemma leb_le : forall n m, (n <=? m)%sint63 = (to_Z n <=? to_Z m)%Z.