Isotopes or isobars?

Each atom in the dictionary is given by its atomic number $Z$ and mass number $A$. You will write a function that says whether two atoms are isotopes, isobars or neither, then count each kind of pair, and find the pairs with the same number of neutrons.

The idea. Isotopes have the same $Z$ and a different $A$. Isobars have the same $A$ and a different $Z$. The neutrons are $A - Z$.

Your tasks.

1. In relation, return "isotopes", "isobars" or "neither".
2. Count n_isotopes and n_isobars over every pair of atoms.
3. Fill same_neutrons with every pair, as a tuple of two names, that has the same number of neutrons.