Write a method that adds an element to a HashSet

Write a static method addIfNotThere$()$ that will add an element to a HashSet only if it does not already exist, and will print out one of the following messages:

Messages:

If the element already exists in the HashSet, the method prints $$element$+"$ already exists in the HashSet$$

If the element is added, the method prints $$element$+"$ was added to the HashSet$$

Parameters: a HashSet of String, and a String to add