Codewars - Digital Root

'''
Digital root is the recursive sum of all the digits in a number.
Given n, take the sum of the digits of n. If that value has more than one digit, continue reducing in this way
until a single-digit number is produced. The input will be a non-negative integer.
Examples
    16  -->  1 + 6 = 7
   942  -->  9 + 4 + 2 = 15  -->  1 + 5 = 6
132189  -->  1 + 3 + 2 + 1 + 8 + 9 = 24  -->  2 + 4 = 6
493193  -->  4 + 9 + 3 + 1 + 9 + 3 = 29  -->  2 + 9 = 11  -->  1 + 1 = 2
'''

def digitalRoot(n):
    if n <= 0 or n != int(n):
        print("Error while using the function '" + digitalRoot.__name__ + "'")
        return -1000
    if n >= 1 and n <= 9:
        return n
    else:
        N = str(n)
        SUM = 0
        for i in range(len(N)):
            SUM += int(N[i])
        return digitalRoot(SUM)


# MAIN FUNCTION
print(digitalRoot(16))
print(digitalRoot(942))
print(digitalRoot(132189))
print(digitalRoot(493193))