Issue 12003: fixing error in xrange alternative sample
diff --git a/Doc/library/functions.rst b/Doc/library/functions.rst
index 4b63c9f..962a53d 100644
--- a/Doc/library/functions.rst
+++ b/Doc/library/functions.rst
@@ -1464,7 +1464,7 @@
also requires that the number of elements fit in a native C long. If a
larger range is needed, an alternate version can be crafted using the
:mod:`itertools` module: ``islice(count(start, step),
- (stop-start+step-1)//step)``.
+ (stop-start+step-1+2*(step<0))//step)``.
.. function:: zip([iterable, ...])