def METHOD_NAME(self, viz_edge: VizEdge) -> None:
    """Add an edge to the terminal graph.
    Parameters
    ----------
    viz_edge : VizEdge
        A `VizEdge` instance.
    """
    # Take CallNode as an example, instead of "arguments point to CallNode",
    # we want "CallNode points to arguments" in ast-dump form.
    #
    # The direction of edge is typically controlled by the implemented VizParser.
    # Reverse start/end here simply because we leverage default parser implementation.
    if viz_edge.end in self._graph:
        self._graph[viz_edge.end].append(viz_edge.start)
    else:
        self._graph[viz_edge.end] = [viz_edge.start]