Remove last traces of cStringIO.
diff --git a/Doc/library/email.message.rst b/Doc/library/email.message.rst
index 5344b45..f51230c 100644
--- a/Doc/library/email.message.rst
+++ b/Doc/library/email.message.rst
@@ -48,7 +48,7 @@
       :class:`Generator` instance and use its :meth:`flatten` method directly.
       For example::
 
-         from cStringIO import StringIO
+         from io import StringIO
          from email.generator import Generator
          fp = StringIO()
          g = Generator(fp, mangle_from_=False, maxheaderlen=60)