Proof of proveit.logic.booleans.quantification.existence.exists_is_bool theorem

see dependencies

import proveit
%proving exists_is_bool

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

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