Virus, viroid, prion or bacterium?

Seven infectious agents are described by four facts: are they cells, do they have nucleic acid, do they have a protein coat, are they protein only? You will write a function that names the kind of agent, sort all seven, and count the ones that are not cells.

The idea. A bacterium is a cell. A virus is nucleic acid in a protein coat. A viroid is free nucleic acid (RNA) with no coat. A prion is protein only.

Your tasks.

1. Finish kind so that it also names prions, viruses and viroids.
2. Set kinds to a dictionary of each agent and its kind.
3. Set not_cells to the number of agents that are not cells.