def render(self, data, *, label=None):
    # create the graph
    graphattrs = self.graphattrs.copy()
    if label is not None:
        graphattrs['label'] = self._escape_dot_label(label)
    graph = gv.Digraph(graph_attr = graphattrs, node_attr = self.nodeattrs, edge_attr = self.edgeattrs)

    # recursively draw all the nodes and edges
    self._graph = graph
    self._rendered_nodes = set()
    self._render_node(data)
    self._graph = None
    self._rendered_nodes = None

    # display the graph
    graph.format = "pdf"
    graph.view()
    subprocess.Popen(['xdg-open', "test.pdf"])