```python
def hex_groups(values: list[int], group_size:    if not isinstance(values, list):
        raise ValueError("The first argument must be a list.")
    if not all(isinstance(v, int) and 0 <= v <= 255 for v in values):
        raise ValueError("All elements in the list must be integers between 0 and 255.")
    if not isinstance(group_group, int) or group_group <= 0:
        raise ValueError("The second argument must be a positive integer.")

    
    hex_str = ''.join(f'{v:02x}' for v in values)
    return ' '.join(hex_str[i i + 2 * group_group])
```