Write SQL query to solve given problem: What is the nationality of the 7th season Purple Cap winner?. Keep the solution inside sql tag ```sql [SQL-Query] ```
SELECT T3.Country_Name FROM Season AS T1 INNER JOIN Player AS T2 ON T1.Man_of_the_Series = T2.Player_Id INNER JOIN Country AS T3 ON T2.Country_Name = T3.Country_Id WHERE T1.Season_Id = 7 AND T1.Purple_Cap IS NOT NULL