Please don't give me the answer just point me in the right direction, thank you. Also, I need to do this without `isdigit()`.

I am trying to create a program that checks all the characters of a string and if any of them are not natural numbers then the program will return `False` otherwise it will return `True`.

This is what i have so far:

```
numbers = ["0123456789"]

if len(str) > 0:
    for i in str:
        if i not in numbers:
            return False
        else:
            return True

```

I have a few test cases and the problem I'm having is that when I return, the whole program just ends. I need to find a way to include the `else: return True`