Proof of proveit.numbers.number_sets.rational_numbers.rational_neg_within_rational_nonzero theorem

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

%proving rational_neg_within_rational_nonzero

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