[Graph]: add is_directed in FG_graph.
[Graph]: add is_directed in FG_graph.

flashxio/FlashX,flashxio/FlashX,icoming/FlashX,flashxio/FlashX,flashxio/FlashX,icoming/FlashX,icoming/FlashX,icoming/FlashX,icoming/FlashX,flashxio/FlashX,flashxio/FlashX