Fix indentation in doc example.
diff --git a/Doc/tutorial/controlflow.rst b/Doc/tutorial/controlflow.rst
index 52e382e..b1456ae 100644
--- a/Doc/tutorial/controlflow.rst
+++ b/Doc/tutorial/controlflow.rst
@@ -19,14 +19,14 @@
    >>> x = int(input("Please enter an integer: "))
    Please enter an integer: 42
    >>> if x < 0:
-   ...      x = 0
-   ...      print('Negative changed to zero')
+   ...     x = 0
+   ...     print('Negative changed to zero')
    ... elif x == 0:
-   ...      print('Zero')
+   ...     print('Zero')
    ... elif x == 1:
-   ...      print('Single')
+   ...     print('Single')
    ... else:
-   ...      print('More')
+   ...     print('More')
    ...
    More