Use universal construct os.path.expanduser('~') instead of os.environ['HOME']
diff --git a/Doc/library/readline.rst b/Doc/library/readline.rst
index f6e855e..64c61a2 100644
--- a/Doc/library/readline.rst
+++ b/Doc/library/readline.rst
@@ -211,7 +211,7 @@
 
    import os
    import readline
-   histfile = os.path.join(os.environ["HOME"], ".pyhist")
+   histfile = os.path.join(os.path.expanduser("~"), ".pyhist")
    try:
        readline.read_history_file(histfile)
    except IOError: