code: def tmpl_alphanum(self, text):
          
          text = self.tmpl_asciify(text)
          text = re.sub(r'[^a-zA-Z0-9]+', ' ', text)
          return re.sub(r'\s+', ' ', text)
docs: * synopsis: ``%alphanum{text}``
          * description: This function first ASCIIfies the given text, then all \
              non alpanumeric characters are replaced with whitespaces.