Issue #25523: Correct "a" article to "an" article
This changes the main documentation, doc strings, source code comments, and a
couple error messages in the test suite. In some cases the word was removed
to fix the grammar.
diff --git a/Doc/library/optparse.rst b/Doc/library/optparse.rst
index dfb43a1..c1ed15b 100644
--- a/Doc/library/optparse.rst
+++ b/Doc/library/optparse.rst
@@ -1327,7 +1327,7 @@
the list of arguments to process (default: ``sys.argv[1:]``)
``values``
- a :class:`optparse.Values` object to store option arguments in (default: a
+ an :class:`optparse.Values` object to store option arguments in (default: a
new instance of :class:`Values`) -- if you give an existing object, the
option defaults will not be initialized on it