fix header punctuation

Author: nedbat

Doc/library/ast.rst

@@ -2201,7 +2201,7 @@ Async and await
 
 
 :mod:`!ast` helpers
-------------------
+-------------------
 
 Apart from the node classes, the :mod:`!ast` module defines these utility functions
 and classes for traversing abstract syntax trees:

Doc/library/atexit.rst

@@ -79,7 +79,7 @@ a cleanup function is undefined.
 .. _atexit-example:
 
 :mod:`!atexit` Example
----------------------
+----------------------
 
 The following simple example demonstrates how a module can initialize a counter
 from a file when it is imported and save the counter's updated value

Doc/library/optparse.rst

@@ -816,7 +816,7 @@ The following two methods can be used to print and get the ``version`` string:
 .. _optparse-how-optparse-handles-errors:
 
 How :mod:`!optparse` handles errors
-^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 There are two broad classes of errors that :mod:`!optparse` has to worry about:
 programmer errors and user errors.  Programmer errors are usually erroneous
@@ -1971,7 +1971,7 @@ arguments::
 .. _optparse-extending-optparse:
 
 Extending :mod:`!optparse`
--------------------------
+--------------------------
 
 Since the two major controlling factors in how :mod:`!optparse` interprets
 command-line options are the action and type of each option, the most likely

Doc/library/subprocess.rst

@@ -28,7 +28,7 @@ modules and functions can be found in the following sections.
 .. include:: ../includes/wasm-mobile-notavail.rst
 
 Using the :mod:`!subprocess` Module
-----------------------------------
+-----------------------------------
 
 The recommended approach to invoking subprocesses is to use the :func:`run`
 function for all use cases it can handle. For more advanced use cases, the
@@ -1346,7 +1346,7 @@ calls these functions.
 .. _subprocess-replacements:
 
 Replacing Older Functions with the :mod:`!subprocess` Module
------------------------------------------------------------
+------------------------------------------------------------
 
 In this section, "a becomes b" means that b can be used as a replacement for a.
 

Doc/library/test.rst

@@ -39,7 +39,7 @@ written using a "traditional" testing style that compares output printed to
 .. _writing-tests:
 
 Writing Unit Tests for the :mod:`!test` package
-----------------------------------------------
+-----------------------------------------------
 
 It is preferred that tests that use the :mod:`unittest` module follow a few
 guidelines. One is to name the test module by starting it with ``test_`` and end

Doc/library/urllib.request.rst

@@ -1486,7 +1486,7 @@ some point in the future.
 
 
 :mod:`!urllib.request` Restrictions
-----------------------------------
+-----------------------------------
 
 .. index::
    pair: HTTP; protocol