How to use the pytmx.pytmx.TiledObjectGroup function in PyTMX

def visible_object_groups(self):
        """Return iterator of object group indexes that are set 'visible'

        :rtype: Iterator
        """
        return (i for (i, l) in enumerate(self.layers)
                if l.visible and isinstance(l, TiledObjectGroup))

:return: self
        """
        self._set_properties(node)
        self.background_color = node.get('backgroundcolor',
                                         self.background_color)

        # ***         do not change this load order!         *** #
        # ***    gid mapping errors will occur if changed    *** #
        for subnode in node.findall('layer'):
            self.add_layer(TiledTileLayer(self, subnode))

        for subnode in node.findall('imagelayer'):
            self.add_layer(TiledImageLayer(self, subnode))

        for subnode in node.findall('objectgroup'):
            self.add_layer(TiledObjectGroup(self, subnode))

        for subnode in node.findall('tileset'):
            self.add_tileset(TiledTileset(self, subnode))

        # "tile objects", objects with a GID, have need to have their attributes
        # set after the tileset is loaded, so this step must be performed last
        # also, this step is performed for objects to load their tiles.

        # tiled stores the origin of GID objects by the lower right corner
        # this is different for all other types, so i just adjust it here
        # so all types loaded with pytmx are uniform.

        # iterate through tile objects and handle the image
        for o in [o for o in self.objects if o.gid]:

            # gids might also have properties assigned to them