Spot the change

You will write three functions that sort a change in oxidation number into oxidation, reduction or disproportionation.

The idea. An atom is oxidised when its oxidation number rises and reduced when it falls. In a disproportionation the same element goes both up and down from one starting number.

Your tasks.

1. In change, return the new oxidation number minus the old one.
2. In kind, return "oxidised", "reduced" or "unchanged" for a single change.
3. In disproportionates, return True if, from the starting number start, some of the numbers in the list ends are higher and some are lower.