Add new GraphTopologyDeletion trait for Graph to implement

src/traits.rs

@@ -13,3 +13,8 @@ pub trait GraphTopology {
     fn add_vertex(&mut self) -> Self::Vertex;
     fn add_edge(&mut self, v1: Self::Vertex, v2: Self::Vertex) -> Self::Edge;
 }
+
+pub trait GraphTopologyDeletion: GraphTopology {
+    fn delete_vertex(&mut self, v: Self::Vertex);
+    fn delete_edge(&mut self, e: Self::Edge);
+}