int a=3;
int b=2;
int c=1;
orderInPlace(a,b,c);
// a is now 1
// b is now 2
// c is now 3
Also a functional variant, say `order(a, b, c)`, that returns a
tuple would also be nice.
See also https://stackoverflow.com/questions/21102646/in-place-ordering-of-elements.
