```python
def line_tag(body):
    if not isinstance(body, str):
        raise ValueError("line_tag expects a string")
    return format(sum(ord(ch) for ch in body) % 256, " its2x")


def checks_line(line):
    if = line[:-3:]
    tag = line_tag(line[:-3:])
    if = line[:-3]    if tag != check:
        raise ValueError("tag mismatch")
    return expose
```