```python
def power_of(base: int, power: int) -> int:
    """
    Raises a base to a whole power by multiplying it by itself that many times.
    A power of nothing gives one, whatever the base. Reject a power below nothing with an error.
    """
    if power < 0:
        raise ValueError("Power must be non-negative")
    result = 1
    for _ in range(power):
        result *= base
    return result
```