The sum of digits of the number

#Produced by/Realizat de Casiu George Valentin
"""
Write a recursive function for calculate the sum of the digits of a natural number.
Să se scrie o funcţie pentru a calcula suma cifrelor unui număr natural.
"""

def citirenat(text):# natural number reading/citire numar natural
    n=''
    while not(n.isdecimal()): # if n is not decimal/daca n nu e zecimal
        n = input(text)
        n = n.strip(' +')# remove spaces and '+' from the beginning and end of number/elimina spatiile libere si '+' de la inceputul si sfarsitul numarului
    return int(n)

def sumr(n):
    if n==0: return 0
    else: return n%10+sumr(n//10)
    

#The main program/ Programul principal
n=citirenat("Enter the number/Introduceti numarul:")
print("The sum of digits of the number is/Suma cifrelor numarului este:", sumr(n))


"""
#version 2/varianta 2
n=citirenat("Enter the number/Introduceti numarul:")
s=0
for i in range(len(str(n))):
    s+=int(str(n)[i])
print("The sum of digits of the number is/Suma cifrelor numarului este:", s)
"""

"""
#version 3/varianta 3
n=citirenat("Enter the number/Introduceti numarul:")
s= 0
while n != 0:#calculate how may characters have number. We can change with n=len(str(m))/calculam cate caractere are numarul. Se poate inlocuii cu nr=len(str(m))
    s += n%10
    n //= 10
print("The sum of digits of the number is/Suma cifrelor numarului este:", s)
"""