Same reason ruby has both "if" and "Unless", or capybara has .to_not as well as .not_to... there are times when the inverse expression is just more natural and

Same reason ruby has both "if" and "Unless", or capybara has .to_not as well as .not_to... there are times when the inverse expression is just more natural and less confusing. Rubocop, on the other hand against what I've just said, will tell you in almost every case that you might use Unless, or in agreement with what I think it is that You are saying here, the preferred idiom is to not use the inverse, and you should only say "unless" when what you meant to say is unambiguously !if. IOW sometimes you really mean reject