def get_doc(logger=None, plugin=None, reporthook=None):
    from ginga.GingaPlugin import GlobalPlugin, LocalPlugin
    if isinstance(plugin, GlobalPlugin):
        plugin_page = 'plugins_global'
        plugin_name = str(plugin)
    elif isinstance(plugin, LocalPlugin):
        plugin_page = 'plugins_local'
        plugin_name = str(plugin)
    else:
        plugin_page = None
        plugin_name = None
    try:
        index_html = _download_rtd_zip(reporthook=reporthook)
    except Exception as e:
        url = 'https://ginga.readthedocs.io/en/latest/'
        if plugin_name is not None:
            if toolkit.family.startswith('qt'):
                url = None
            else:
                url += 'manual/{}/{}.html'.format(plugin_page, plugin_name)
        if logger is not None:
            logger.error(str(e))
    else:
        pfx = 'file:'
        url = '{}{}'.format(pfx, index_html)
        if plugin_name is not None:
            url += '
    return url