Update Graph::are_adjacent() to use neighbors() iterator

src/models.rs

@@ -61,20 +61,8 @@ impl Graph {
         self.incidence_headers[v.0].incidence_count
     }
 
-    // TODO: 'fn are_adjacent()' could probably be done with a neighbor vertex iterator.
     pub fn are_adjacent(&self, v1: Vertex, v2: Vertex) -> bool {
-        let Some(mut incidence) = self.incidence_headers[v1.0].first_incidence else {
-            return false;
-        };
-        loop {
-            if self.incidence_vertices[incidence.0] == v2 {
-                return true;
-            }
-            let Some(next) = self.next_incidences[incidence.0] else {
-                return false;
-            };
-            incidence = next;
-        }
+        self.neighbors(v1).find(|&x| x == v2).is_some()
     }
 
     // TODO: 'fn add_vertex()' needs variants for custom vertex data.