Proof of proveit.logic.sets.comprehension.in_superset_if_in_comprehension theorem

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

%proving in_superset_if_in_comprehension

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