intros A B.
red in |- *.
intro.
simpl in |- *.
red in |- *.
intro i.
simpl in |- *.
apply MONOID_unit_r.
Qed.

Lemma func_zerofun_is_l_unit :
forall (A : Setoid) (B : monoid),
unit_l (sgroup_law_map (func_sgroup A B)) (func_zerofun A B).