def METHOD_NAME(pdus: List[dict], filename_prefix: str) -> None:
    """
    Generate a dot and SVG file for a graph of events in the room based on the
    topological ordering by querying a homeserver.
    """
    pdu_map = {}
    node_map = {}
    origins = set()
    colors = {"red", "green", "blue", "yellow", "purple"}
    for pdu in pdus:
        origins.add(pdu.get("origin"))
    color_map = {color: color for color in colors if color in origins}
    colors -= set(color_map.values())
    color_map[None] = "black"
    for o in origins:
        if o in color_map:
            continue
        try:
            c = colors.pop()
            color_map[o] = c
        except Exception:
            print("Run out of colours!")
            color_map[o] = "black"
    graph = pydot.Dot(graph_name="Test")
    for pdu in pdus:
        name = make_name(pdu.get("pdu_id"), pdu.get("origin"))
        pdu_map[name] = pdu
        t = datetime.datetime.fromtimestamp(float(pdu["ts"]) / 1000).strftime(
            "%Y-%m-%d %H:%M:%S,%f"
        )
        label = (
            "<"
            "<b>%(name)s </b><br/>"
            "Type: <b>%(type)s </b><br/>"
            "State key: <b>%(state_key)s </b><br/>"
            "Content: <b>%(content)s </b><br/>"
            "Time: <b>%(time)s </b><br/>"
            "Depth: <b>%(depth)s </b><br/>"
            ">"
        ) % {
            "name": name,
            "type": pdu.get("pdu_type"),
            "state_key": pdu.get("state_key"),
            "content": cgi.escape(json.dumps(pdu.get("content")), quote=True),
            "time": t,
            "depth": pdu.get("depth"),
        }
        node = pydot.Node(name=name, label=label, color=color_map[pdu.get("origin")])
        node_map[name] = node
        graph.add_node(node)
    for pdu in pdus:
        start_name = make_name(pdu.get("pdu_id"), pdu.get("origin"))
        for i, o in pdu.get("prev_pdus", []):
            end_name = make_name(i, o)
            if end_name not in node_map:
                print("%s not in nodes" % end_name)
                continue
            edge = pydot.Edge(node_map[start_name], node_map[end_name])
            graph.add_edge(edge)
        # Add prev_state edges, if they exist
        if pdu.get("prev_state_id") and pdu.get("prev_state_origin"):
            prev_state_name = make_name(
                pdu.get("prev_state_id"), pdu.get("prev_state_origin")
            )
            if prev_state_name in node_map:
                state_edge = pydot.Edge(
                    node_map[start_name], node_map[prev_state_name], style="dotted"
                )
                graph.add_edge(state_edge)
    graph.write("%s.dot" % filename_prefix, format="raw", prog="dot")
    #    graph.write_png("%s.png" % filename_prefix, prog='dot')
    graph.write_svg("%s.svg" % filename_prefix, prog="dot")