Fact eq_rect_combine_dist_helper1 : forall a b c d, b * c = d -> (a + b) * c = a * c + d.Fact eq_rect_combine_dist_helper2 : forall a b c d, b * c = d -> a * c + d = (a + b) * c.

Lemma wzero_rev : forall (a b : nat) H, wzero (a + b) = eq_rect _ word (wzero (b + a)) _ H.