From 7045c41418a5497ea616baa2c71b91d9bf2a945b Mon Sep 17 00:00:00 2001
From: Dan Gohman <sunfish@mozilla.com>
Date: Tue, 29 May 2018 19:26:13 -0700
Subject: [PATCH] Add a comment about implementing `Keys` in terms of `Range`
 in the future.

---
 lib/entity/src/keys.rs | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/lib/entity/src/keys.rs b/lib/entity/src/keys.rs
index e9d1e91505..4301bbe689 100644
--- a/lib/entity/src/keys.rs
+++ b/lib/entity/src/keys.rs
@@ -1,4 +1,7 @@
 //! A double-ended iterator over entity references.
+//!
+//! When `std::iter::Step` is stablized, `Keys` could be implemented as a wrapper around
+//! `std::ops::Range`, but for now, we implment it manually.
 
 use EntityRef;
 use std::marker::PhantomData;