def opt_allow_ignore_ext(self):
        """
        Specify whether or not a request for 'foo' should return 'foo.ext'
        """
        if not isinstance(self['root'], static.File):
            raise usage.UsageError("You can only use --allow_ignore_ext "
                                   "after --path.")
        self['root'].ignoreExt('*')

        Specify whether or not a request for 'foo' should return 'foo.ext'
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/web/tap.py