Mubashir needs your help to find out the next happy year.
A Happy Year is the year with only distinct digits. Create a function that takes an integer year and returns the next happy year.
happy_year(2017) ➞ 2018
# 2018 has all distinct digits
happy_year(1990) ➞ 2013
happy_year(2021) ➞ 2031
N/A