message: remove Graph::sort as it is unused
diff: @@ -6,11 +6,6 @@ pub struct Graph<N, E> {
  nodes: HashMap<N, HashMap<N, E>>,
  }
  -enum Mark {
  - InProgress,
  - Done,
  -}
  -
  pub type Nodes<'a, N, E> = Keys<'a, N, HashMap<N, E>>;
  pub type Edges<'a, N, E> = Iter<'a, N, E>;
  @@ -41,32 +36,6 @@ impl<N: Eq + Hash + Clone, E: Default> Graph<N, E> {
  self.nodes.get(from).map(|set| set.iter())
  }
  - pub fn sort(&self) -> Option<Vec<N>> {
  - let mut ret = Vec::new();
  - let mut marks = HashMap::new();
  -
  - for node in self.nodes.keys() {
  - self.visit(node, &mut ret, &mut marks);
  - }
  -
  - Some(ret)
  - }
  -
  - fn visit(&self, node: &N, dst: &mut Vec<N>, marks: &mut HashMap<N, Mark>) {
  - if marks.contains_key(node) {
  - return;
  - }
  -
  - marks.insert(node.clone(), Mark::InProgress);
  -
  - for child in self.nodes[node].keys() {
  - self.visit(child, dst, marks);
  - }
  -
  - dst.push(node.clone());
  - marks.insert(node.clone(), Mark::Done);
  - }
  -
  pub fn iter(&self) -> Nodes<N, E> {
  self.nodes.keys()
  }
  