Sort the amines

You will write functions that sort an amine by the groups on its nitrogen atom. The groups are given as a list such as ["CH3", "H", "H"]. A hydrogen atom is written as "H".

The idea. The class of an amine is the number of carbon groups on the nitrogen. Hydrogen atoms do not count. An amine is aromatic only when the nitrogen is joined straight to a benzene ring, written as the group "C6H5".

Your tasks.

1. Complete carbon_groups(groups) so that it returns how many of the three positions hold a carbon group.
2. Complete classify(groups) so that it returns "primary", "secondary" or "tertiary".
3. Complete is_aromatic(groups) so that it returns True when one of the groups is exactly "C6H5".