Configurations of the first series

You will write functions that give the configuration of an atom of the 3d series and of its ions. You will also test whether an element is a transition element.

The idea. The $4s$ orbital holds 2 electrons, except for chromium ($Z = 24$) and copper ($Z = 29$), which hold 1. The other electrons beyond argon sit in $3d$. An ion loses its $4s$ electrons first.

Your tasks.

1. Complete config(z) so that it returns the electrons in (3d, 4s) for the atom.
2. Complete d_in_ion(z, charge) so that it returns the electrons in $3d$ for the ion with that positive charge.
3. Complete is_transition(z, charges) so that it returns True if the atom or any of the ions has between 1 and 9 electrons in $3d$.