def get_icon(brain_or_object, html_tag=True):
    """Get the icon of the content object

    :param brain_or_object: A single catalog brain or content object
    :type brain_or_object: ATContentType/DexterityContentType/CatalogBrain
    :param html_tag: A value of 'True' returns the HTML tag, else the image url
    :type html_tag: bool
    :returns: HTML '<img>' tag if 'html_tag' is True else the image url
    :rtype: string
    """
    # Manual approach, because `plone.app.layout.getIcon` does not reliable
    # work for Bika Contents coming from other catalogs than the
    # `portal_catalog`
    portal_types = get_tool("portal_types")
    fti = portal_types.getTypeInfo(brain_or_object.portal_type)
    icon = fti.getIcon()
    if not icon:
        return ""
    url = "%s/%s" % (get_url(get_portal()), icon)
    if not html_tag:
        return url
    tag = '<img width="16" height="16" src="{url}" title="{title}" />'.format(
        url=url, title=get_title(brain_or_object))
    return tag