A happy number is a number which yields a 1 by repeatedly summing up the square of its digits. 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.
is_happy(67) ➞ False
is_happy(89) ➞ False
is_happy(139) ➞ True
is_happy(1327) ➞ False
is_happy(2871) ➞ False
is_happy(3970) ➞ True
n is either 1 or 4.