Move edge_count() in method order

src/traits.rs

@@ -9,9 +9,9 @@ pub trait GraphTopology {
     type Edge: Copy + Eq;
 
     fn vertex_count(&self) -> usize;
-    fn edge_count(&self) -> usize;
     fn vertex_capacity(&self) -> usize;
     fn vertex_map<T: Clone>(&self, default: T) -> VertexMap<Self::Vertex, T>;
+    fn edge_count(&self) -> usize;
     fn degree(&self, v: Self::Vertex) -> usize;
     fn are_adjacent(&self, v1: Self::Vertex, v2: Self::Vertex) -> bool;
     fn vertices(&self) -> impl Iterator<Item = Self::Vertex>;