Fun! This can also be found as a general array accessor:

https://github.com/rails/rails/blob/ed03d4eaa89a7b4ab09e7f5d...

Here's another interesting one from ActiveSupport giving Ruby Numerics the ability to be treated as various quantities of bytes:

https://github.com/rails/rails/blob/9eeb5fed2ff8e781e56202f6...