def undisplayable_info(obj, html=False):
    "Generate helpful message regarding an undisplayable object"

    collate = '<tt>collate</tt>' if html else 'collate'
    info = "For more information, please consult the Composing Data tutorial (http://git.io/vtIQh)"
    if isinstance(obj, HoloMap):
        error = "HoloMap of %s objects cannot be displayed." % obj.type.__name__
        remedy = "Please call the %s method to generate a displayable object" % collate
    elif isinstance(obj, Layout):
        error = "Layout containing HoloMaps of Layout or GridSpace objects cannot be displayed."
        remedy = "Please call the %s method on the appropriate elements." % collate
    elif isinstance(obj, GridSpace):
        error = "GridSpace containing HoloMaps of Layouts cannot be displayed."
        remedy = "Please call the %s method on the appropriate elements." % collate

    if not html:
        return '\n'.join([error, remedy, info])
    else:
        return "<center>{msg}</center>".format(msg=('<br>'.join(
            ['<b>%s</b>' % error, remedy, '<i>%s</i>' % info])))