Interestingly you can do this:

    class Foo:
        def bar(self):
            return "bar"

    foo = Foo()
    foo.bar()      # returns "bar"
    Foo.bar(foo)   # returns "bar"

So it's not actually specifying `self` for instance methods; it's just a special thing about class instances that calling a method will call its class's method passing the instance as the first argument.

After realizing this, I was enlightened.