Proof of proveit.numbers.exponentiation.exp_even_neg_base_lesseq theorem

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

%proving exp_even_neg_base_lesseq

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