Local Notation "[+| c |]" :=
   (interp_carry 1 wB to_Z c)  (at level 0, c at level 99) : uint63_scope.Local Notation "[-| c |]" :=
   (interp_carry (-1) wB to_Z c)  (at level 0, c at level 99) : uint63_scope.

Lemma to_Z_inj x y : φ x = φ y → x = y.