docs: def _write(self, level, correlation_id, error, message):
          """
          Writes a log message to the logger destination.
  
          :param level: a log level.
  
          :param correlation_id: (optional) transaction id to trace execution through call chain.
  
          :param error: an error object associated with this message.
  
          :param message: a human-readable message to log.
          """
          if (self._level < level):
              return
  
          output = "["
          output += correlation_id if correlation_id != None else "---"
          output += ":"
          output += LogLevelConverter.to_string(level)
          output += ":"
          output += datetime.datetime.utcnow().isoformat()
          output += "] "
  
          output += message
  
          if error != None:
              if len(message) == 0:
                  output += "Error: "
              else:
                  output += ": "
  
              output += self._compose_error(error)
  
          output += "\n"
  
          if level >= LogLevel.Fatal and level <= LogLevel.Warn:
              sys.stderr.write(output)
          else:
              sys.stdout.write(output)