This code is solving the below mentioned assessment
Create an in-memory store for recently played songs that can accommodate N songs per user, with a fixed initial capacity. This store must have the capability to store a list of song-user pairs, with each song linked to a user. It should also be able to fetch recently played songs based on the user and eliminate the least recently played songs when the store becomes full.
EXAMPLE when 4 different songs were played by a user & Initial capacity is 3: Let's assume that the user has played 3 songs - S1, S2 and S3. The playlist would look like -> S1,S2,S3 When S4 song is played -> S2,S3,S4 When S2 song is played -> S3,S4,S2 When S1 song is played -> S4,S2,S1