Proof of proveit.logic.booleans.implication.not_iff_via_not_left theorem

import proveit
theory = proveit.Theory() # the theorem's theory

%proving not_iff_via_not_left

With these allowed/disallowed theorem/theory presumptions (e.g., to avoid circular dependencies), we begin our proof of
not_iff_via_not_left:
(see dependencies)

not_iff_via_not_left may now be readily provable (assuming required theorems are usable).  Simply execute "%qed".