Proof of proveit.numbers.addition.unary_add_reduction theorem

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

%proving unary_add_reduction

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

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