Set Bullet Behavior "Strict Subproofs".
Opaque upto.

Lemma make_shares_ext : forall i l l' shs (Hlen : Zlength l = Zlength l')
(Hi : forall j, 0 <= j < Zlength l -> Znth j l = i <-> Znth j l' = i),
make_shares shs l i = make_shares shs l' i.