def parse_comment(line):
    """
    Parse special comment such as ``#+SEQ_TODO``

    >>> parse_comment('#+SEQ_TODO: TODO | DONE')
    ('SEQ_TODO', 'TODO | DONE')
    >>> parse_comment('# not a special comment')  # None

    """
    if line.startswith('#+'):
        comment = line.lstrip('#+').split(':', 1)
        if len(comment) == 2:
            return comment[0], comment[1].strip()
