Link to a Bokeh Github issue.

    Returns 2 part tuple containing list of nodes to insert into the
    document and a list of system messages.  Both are allowed to be
    empty.

def bokeh_issue(name, rawtext, text, lineno, inliner, options=None, content=None):
    ''' Link to a Bokeh Github issue.

    Returns 2 part tuple containing list of nodes to insert into the
    document and a list of system messages.  Both are allowed to be
    empty.

    '''
    app = inliner.document.settings.env.app
    try:
        issue_num = int(text)
        if issue_num <= 0:
            raise ValueError
    except ValueError:
        msg = inliner.reporter.error(
            'Github issue number must be a number greater than or equal to 1; '
            '"%s" is invalid.' % text, line=lineno)
        prb = inliner.problematic(rawtext, rawtext, msg)
        return [prb], [msg]
    node = _make_gh_link_node(app, rawtext, 'issue', '#', 'issues', str(issue_num), options)
    return [node], []