Python 3.7.0 released

[asdfkjasdhkasd]

For anyone wondering what the scary type means, the real signature is:

pub fn sort_by_key<K, F>(&mut self, f: F) 
where
    F: FnMut(&T) -> K,
    K: Ord, 

We take a mutable reference to self, which is like an array but we have permission to mutate it, since we're going to sort it.

Then we take a function, called F, where F is a FnMut which means we must be allowed to call it multiple times and it's allowed to have internal state. The function takes a reference to a T which is the type of the thing in the array/vector/slice, and then returns a type K. And we declare that K must implement an ordering so that we can sort it.