def make_basename(self, fn=None, ext=None):
fb, oldext = os.path.splitext(os.path.basename(fn or self.fn))<EOL>ext = ext or oldext.lower()<EOL>fb = String(fb).hyphenify(ascii=True)<EOL>return '<STR_LIT>'.join([fb, ext])<EOL>
make a filesystem-compliant basename for this file