message: Don't suggest use of usize instead of u32
  usize machine dependent and on x86 machines it is the same as `u32`. Instead use a machine independent size e.g. `u64` or `u128`.
diff: @@ -303,7 +303,7 @@ impl<E, Ix: IndexType> Edge<E, Ix>
  /// take its place. Similarly, removing an edge shifts the index of the last edge.
  ///
  /// The `Ix` parameter is `u32` by default. The goal is that you can ignore this parameter
  -/// completely unless you need a very big graph -- then you can use `usize`.
  +/// completely unless you need a very big graph -- then you can use `u64` or `u128`.
  ///
  /// ### Pros and Cons of Indices
  ///
  