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

def add_layer(self, layer):
        """ Add a layer (TileTileLayer, TiledImageLayer, or TiledObjectGroup)

        :param layer: TileTileLayer, TiledImageLayer, TiledObjectGroup object
        """
        assert (
            isinstance(layer,
                       (TiledTileLayer, TiledImageLayer, TiledObjectGroup)))

        self.layers.append(layer)
        self.layernames[layer.name] = layer

def parse_xml(self, node):
        """ Parse a map from ElementTree xml node

        :param node: ElementTree xml node
        :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

:param x: x coordinate
        :param y: y coordinate
        :param layer: layer number
        :rtype: surface if found, otherwise 0
        """
        try:
            assert (x >= 0 and y >= 0)
        except AssertionError:
            raise ValueError

        try:
            layer = self.layers[layer]
        except IndexError:
            raise ValueError

        assert (isinstance(layer, TiledTileLayer))

        try:
            gid = layer.data[y][x]
        except (IndexError, ValueError):
            raise ValueError
        except TypeError:
            msg = "Tiles must be specified in integers."
            logger.debug(msg)
            raise TypeError

        else:
            return self.get_tile_image_by_gid(gid)