Hello! I write this code:
def digit_sum(n): res = 0 ints =  if n >= 0 and n - float(n) == 0: n = str(n) i = 0 in1 = 0 while i != len(n) - 1: ints.append(n[i]) i += 1 while in1 != len(ints) - 1: res = res + ints[in1] in1 += 1 else: print res
and got this message:
"list index out of range error"
Where I made a mistake? I absolutely don't understand how to write this program. Help me, please if you can.