Currently there are the following functions: * `post_order_dfs_vertices` * `post_order_dfs_edges` * `pre_order_dfs_vertices` So it could be good to add `pre_order_dfs_edges`.
Currently there are the following functions:
post_order_dfs_verticespost_order_dfs_edgespre_order_dfs_verticesSo it could be good to add
pre_order_dfs_edges.