We use a "dictionary of sets" to store equivalences for the problems below: each value is associated with a set of all the values it is equivalent to. For example, let us define an equivalence of birthdays. If people named 'a', 'b', and 'c' had equivalent birthdays (born on the same day, regardless of the year), and people named 'd', and 'e' had equivalent birthdays, and no one else had the same birthday as 'f', then we could represent this information in the following equivalence dictionary: in it each person's name is a key, and each key is associated with the set of names of people who have the same birthday (are equivalent). ed = {'a': {'a', 'b', 'c'}, 'b': {'a', 'b', 'c'}, 'c': {'a', 'b', 'c'}, 'd': {'d', 'e'}, 'e': {'d', 'e'}, 'f': {'f'}} Define a function equiv that takes three arguments: an equivalence dictionary and two strings (names): it returns True whenever the two names are equivalent, otherwise False: equiv (ed, 'a', 'b') returns True