Hello there fine madam or sir!
I have a short quiz for you. It won't take long.
By the way, don't worry if there are questions you can't answer. Lots of people will be struggling along with you, so don't feel bad. You're not alone.
Do you recognize the method for which this is the (simplified) source?
def mystery_method(accumulator) each do |element| accumulator = yield accumulator, element end accumulator end