def METHOD_NAME(data):
    """
    A pre_transform function that transfers the directed graph into undirected graph.
    Args:
        data (torch_geometric.data.Data): Directed graph in the format :class:`torch_geometric.data.Data`.
        where the :obj:`data.x`, :obj:`data.edge_index` are required.
    """
    data.edge_index = torch.cat([torch.stack([data.edge_index[1], data.edge_index[0]], dim=0),
                                 data.edge_index], dim=1)
    return data