def _next_token(iterable, comments):
    """
	Yields only non-whitespace, non-comment lines.
	"""
    for line in iterable:
        parts = iter(line.strip().split(None, 1))
        key = next(parts, None)
        if not key:
            continue
        elif key == b'COMMENT':
            comments.append(next(parts, b''))
        else:
            yield key, next(parts, None)
