TODO
Used to have this as default on charkeys but that seemed like a questionable default
it('should group keys with same first letter by array', ()=> {
const input = {
xylophone: 1,
xonkey: 2,
xebra: 3,
zebra: 4
};
const output = somethingsomething(input);
Assert.deepEqual(output, {x: [1, 2, 3], z: 4});
});