From 5030b355ddd55754a639e323b832e91282f85f2d Mon Sep 17 00:00:00 2001
From: mautamu <mautam@usa.com>
Date: Wed, 29 Sep 2021 19:07:27 -0500
Subject: [PATCH] Close #1464

Adds a `main` function to the last impl Trait example that demonstrates the expected behavior.
---
 src/trait/impl_trait.md | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/src/trait/impl_trait.md b/src/trait/impl_trait.md
index 7b87bd2e9c..f429d9adf7 100644
--- a/src/trait/impl_trait.md
+++ b/src/trait/impl_trait.md
@@ -68,4 +68,10 @@ fn double_positives<'a>(numbers: &'a Vec<i32>) -> impl Iterator<Item = i32> + 'a
         .filter(|x| x > &&0)
         .map(|x| x * 2)
 }
+
+fn main() {
+    let singles = vec![-3, -2, 2, 3];
+    let doubles = double_positives(&singles);
+    assert_eq!(doubles.collect::<Vec<i32>>(), vec![4, 6]);
+}
 ```