------
## 最终结论
```python
def string_sequence(n: int) -> str:
    """ Return a string containing space-delimited numbers starting from 0 upto n inclusive.
    >>> string_sequence(0)
    '0'
    >>> string_sequence(5)
    '0 1 2 3 4 5'
    """
    numbers = range(n + 1)
    result = ' '.join(map(str, numbers))
    return result
```