An instructor has given her student an assignment to calculate the sum of the digits of a positive integer using recursion.The student came up with the solution but the solution does not seem to be correct. Help her fix the error.
sum_digit(111) ➞ 3
# 1 + 1 + 1 = 3
sum_digit(222) ➞ 6
# 2 + 2 + 2 = 6
sum_digit(333) ➞ 9
# 3 + 3 + 3 = 9Input is a positive integer.