Deals Of The Week - hours only!Up to 80% off on all courses and bundles.-Close
Recap
Using sets to compute unique elements
4. Creating lists with unique elements
Set operations
Simulating machines
Summary

## Instruction

Good job! In the previous exercise, we created a set based on a list with duplicate elements. If we want to create a new list without duplicates, we only need one more operation:

cities = ['London', 'Madrid', 'Milan', 'Bordeaux', 'Milan', 'London', 'Lisbon', 'London']
unique_cities = list(set(cities))

We first created a set with unique values by using set(cities). Then we created a list based on the set using list(set(cities)). Note that the order of elements in the list may not be the same as in the original list.

## Exercise

John, Mark and Stephanie listened to some songs, sometimes a few times to the same song if they liked it :). We stored the songs they listened to in the order they listened to them in a dictionary named songs_in_order. Now we'd like to create a playlist for each listener. In the playlist, each song should occure only once.

Create a dictionary named playlists, in which you will store a list of the songs listened to by John, Mark, and Stephanie (in no particular order). Any song that was played many times should occur only once in the list.