diff -r a36d469f31c1 Doc/tutorial/datastructures.rst
--- a/Doc/tutorial/datastructures.rst	Sun Aug 03 15:26:32 2014 -0400
+++ b/Doc/tutorial/datastructures.rst	Wed Sep 10 15:14:03 2014 -0400
@@ -194,12 +194,16 @@
    >>> squares
    [0, 1, 4, 9, 16, 25, 36, 49, 64, 81]
 
-We can obtain the same result with::
+Note that this creates (or overwrites) a variable named x in the surrounding
+scope.  We can calculate the list of squares without any side effects, using::
+
+   squares = list(map(lambda x: x**2, range(10)))
+
+or equivalently::
 
    squares = [x**2 for x in range(10)]
 
-This is also equivalent to ``squares = list(map(lambda x: x**2, range(10)))``,
-but it's more concise and readable.
+which is more concise and readable.
 
 A list comprehension consists of brackets containing an expression followed
 by a :keyword:`for` clause, then zero or more :keyword:`for` or :keyword:`if`