From c430fa8084277c9ee36b022dd028ed302b3f5afe Mon Sep 17 00:00:00 2001
From: toidiu <toidiu@protonmail.com>
Date: Sat, 9 Sep 2017 16:56:12 -0400
Subject: [PATCH] documentation update to demonstrate mutability

---
 src/liballoc/str.rs | 23 ++++++++++++++++-------
 1 file changed, 16 insertions(+), 7 deletions(-)

diff --git a/src/liballoc/str.rs b/src/liballoc/str.rs
index 79b2bbce2af7..e6b28d4d1c25 100644
--- a/src/liballoc/str.rs
+++ b/src/liballoc/str.rs
@@ -362,16 +362,25 @@ impl str {
     /// # Examples
     ///
     /// ```
-    /// let mut v = String::from("🗻∈🌏");
-    ///
-    /// assert_eq!(Some("🗻"), v.get_mut(0..4).map(|v| &*v));
-    ///
-    /// // indices not on UTF-8 sequence boundaries
-    /// assert!(v.get_mut(1..).is_none());
-    /// assert!(v.get_mut(..8).is_none());
+    /// use std::ascii::AsciiExt;
     ///
+    /// let mut v = String::from("hello");
+    /// // correct length
+    /// assert!(v.get_mut(0..5).is_some());
     /// // out of bounds
     /// assert!(v.get_mut(..42).is_none());
+    /// assert_eq!(Some("he"), v.get_mut(0..2).map(|v| &*v));
+    ///
+    /// assert_eq!("hello", v);
+    /// {
+    ///     let s = v.get_mut(0..2);
+    ///     let s = s.map(|s| {
+    ///         s.make_ascii_uppercase();
+    ///         &*s
+    ///     });
+    ///     assert_eq!(Some("HE"), s);
+    /// }
+    /// assert_eq!("HEllo", v);
     /// ```
     #[stable(feature = "str_checked_slicing", since = "1.20.0")]
     #[inline]