Fix typo in docstring (the module is popen2, not 3).
diff --git a/Lib/subprocess.py b/Lib/subprocess.py
index 11fc439..6ecff25 100644
--- a/Lib/subprocess.py
+++ b/Lib/subprocess.py
@@ -340,7 +340,7 @@
stdin=PIPE, stdout=PIPE, close_fds=True)
(child_stdout, child_stdin) = (p.stdout, p.stdin)
-The popen2.Popen3 and popen3.Popen4 basically works as subprocess.Popen,
+The popen2.Popen3 and popen2.Popen4 basically works as subprocess.Popen,
except that:
* subprocess.Popen raises an exception if the execution fails