code: def block_code(self, text, lang):
          
  
          if not lang:
              return self._code_no_lexer(text)
  
          try:
              lexer = get_lexer_by_name(lang, stripall=True)
          except ClassNotFound:  # lexer not found, use plain text
              return self._code_no_lexer(text)
  
          formatter = HtmlFormatter()
  
          return highlight(text, lexer, formatter)
docs: text: unicode text to render