How to Infer a Type in a Conditional, Conditional Type

A lot of the stuff i couldn't grock until i actually had to solve a problem with it. It's weird that the kind of use the extends keyword, both in generics and in conditionals. There's many examples of this kind of madness that are things you won't find in the handbook. But fortunately, most people will never have to worry about removing question mark from an object type.