Enzymes along the canal

A list gives the enzymes of human digestion in the order the food meets them, with where each is made and the food it acts on. You will list the enzymes that act on proteins, count the enzymes of each part, and find the part with the most. Then the program draws the counts.

The idea. Go through the list in order, and keep the ones you want. A dictionary is good for counting.

Your tasks.

1. In acting_on, return the names of the enzymes that act on the given food, in order.
2. Set per_part to a dictionary of each part and the number of its enzymes.
3. Set busiest to the part with the most enzymes.