Remove trailing whitespace.
diff --git a/Doc/library/stringio.rst b/Doc/library/stringio.rst
index 19e1547..f7f6771 100644
--- a/Doc/library/stringio.rst
+++ b/Doc/library/stringio.rst
@@ -52,7 +52,7 @@
    # 'First line.\nSecond line.\n'
    contents = output.getvalue()
 
-   # Close object and discard memory buffer -- 
+   # Close object and discard memory buffer --
    # .getvalue() will now raise an exception.
    output.close()
 
@@ -81,7 +81,7 @@
 
 Calling :func:`StringIO` with a Unicode string parameter populates
 the object with the buffer representation of the Unicode string, instead of
-encoding the string. 
+encoding the string.
 
 Another difference from the :mod:`StringIO` module is that calling
 :func:`StringIO` with a string parameter creates a read-only object. Unlike an
@@ -118,7 +118,7 @@
    # 'First line.\nSecond line.\n'
    contents = output.getvalue()
 
-   # Close object and discard memory buffer -- 
+   # Close object and discard memory buffer --
    # .getvalue() will now raise an exception.
    output.close()