Recursion: Happy Number

A happy number is a number which yields a 1 by repeatedly summing up the square of its digit. If such a process results in an endless cycle of numbers containing 4, the number is said to be an unhappy number.

Create a function that accepts a number and determines whether the number is a happy number or not. Return True if so, False otherwise.

Examples

is_happy(67) ➞ False

is_happy(89) ➞ False

is_happy(139) ➞ True

is_happy(1327) ➞ False

is_happy(2871) ➞ False

is_happy(3970) ➞ True

Notes

• You are expected to solve this challenge via recursion.
• A non-recursive version of this challenge can be found in here.