#6977: getopt does not support optional option arguments.

Doc/library/getopt.rst

@@ -30,19 +30,20 @@ exception:
 
    .. note::
 
-      Unlike GNU :cfunc:`getopt`, after a non-option argument, all further arguments
-      are considered also non-options. This is similar to the way non-GNU Unix systems
-      work.
+      Unlike GNU :cfunc:`getopt`, after a non-option argument, all further
+      arguments are considered also non-options. This is similar to the way
+      non-GNU Unix systems work.
 
    *long_options*, if specified, must be a list of strings with the names of the
-   long options which should be supported.  The leading ``'-``\ ``-'`` characters
-   should not be included in the option name.  Long options which require an
-   argument should be followed by an equal sign (``'='``).  To accept only long
-   options, *options* should be an empty string.  Long options on the command line
-   can be recognized so long as they provide a prefix of the option name that
-   matches exactly one of the accepted options.  For example, if *long_options* is
-   ``['foo', 'frob']``, the option :option:`--fo` will match as :option:`--foo`,
-   but :option:`--f` will not match uniquely, so :exc:`GetoptError` will be raised.
+   long options which should be supported.  The leading ``'-``\ ``-'``
+   characters should not be included in the option name.  Long options which
+   require an argument should be followed by an equal sign (``'='``).  Optional
+   arguments are not supported.  To accept only long options, *options* should
+   be an empty string.  Long options on the command line can be recognized so
+   long as they provide a prefix of the option name that matches exactly one of
+   the accepted options.  For example, if *long_options* is ``['foo', 'frob']``,
+   the option :option:`--fo` will match as :option:`--foo`, but :option:`--f`
+   will not match uniquely, so :exc:`GetoptError` will be raised.
 
    The return value consists of two elements: the first is a list of ``(option,
    value)`` pairs; the second is the list of program arguments left after the