code: def GetSeverityString(self, severity):
      
      if 0 <= severity < len(self._SEVERITY):
        return self._SEVERITY[severity]
      return 'Unknown {0:d}'.format(severity)
docs: Retrieves a string representation of the severity.
  
      Args:
        severity (int): severity.
  
      Returns:
        str: description of the event severity.