Dictionaries and sets

task 2 :

Write a function called max_length that accepts a set of strings as a parameter and that returns the length of the longest string in the set. If your function is passed an empty set, it should return 0.

task 1:

Write a function is_unique that accepts a dictionary whose keys and values are strings as a parameter and returns True if no two keys map to the same value (and False if any two or more keys do map to the same value).