@staticmethod
def _parse_line(line):
    """Parse a line from an SFM file into a tag and a value."""
    line = line.strip()
    if not line:
        return None, None
    if line[0] == '#':
        return None, None
    parsed = iter(line.split(maxsplit=1))
    tag = next(parsed, None)
    value = next(parsed, None)
    return tag, value
