code: def _handle_parameter(self, default):
          
          key = None
          showkey = False
          self._push()
          while self._tokens:
              token = self._tokens.pop()
              if isinstance(token, tokens.TemplateParamEquals):
                  key = self._pop()
                  showkey = True
                  self._push()
              elif isinstance(token, (tokens.TemplateParamSeparator,
                                      tokens.TemplateClose)):
                  self._tokens.append(token)
                  value = self._pop()
                  if key is None:
                      key = Wikicode(SmartList([Text(str(default))]))
                  return Parameter(key, value, showkey)
              else:
                  self._write(self._handle_token(token))
          raise ParserError("_handle_parameter() missed a close token")
docs: Handle a case where a parameter is at the head of the tokens.
  
          *default* is the value to use if no parameter name is defined.