docs: def format(self, record):
          """
          return log in unicode
          """
          self._format_record(record)
  
          record_dict = {}
          for k, v in record.__dict__.items():
              if isinstance(k, str):
                  k = decode_(k, 'utf8')
              if isinstance(v, str):
                  v = decode_(v, 'utf8', 'replace')
              record_dict[k] = v
  
          if 'color' in self.fmt or 'end_color' in self.fmt:
              record_dict['color'], record_dict['end_color'] = _color(record.levelno)
  
          log = self.ufmt % record_dict
  
          if record.exc_text:
              if log[-1:] != '\n':
                  log += '\n'
              log += decode_(record.exc_text, 'utf8', 'replace')
  
          log = log.replace('\n', '\n' + self.tab)
  
          return log