Plan the route

You will finish a small route planner. Each route to a primary amine has a change in the number of carbon atoms, and notes on whether it gives a pure product and whether it works for an aromatic amine.

The idea. A route starts from a compound with a different number of carbon atoms from the amine. The nitrile route starts with one carbon fewer than the amine, and the Hofmann route with one carbon more.

Your tasks.

1. Complete start_carbons(route, wanted) so that it returns the carbon atoms the starting compound needs.
2. Fill the list pure with the routes that give a pure primary amine (the value True in the second place).
3. Fill the list for_aromatic with the routes that work for an aromatic amine (the value True in the third place).