anchor.diff:              'projects/$projectid/traces/${traceHeader.split('/')[0]}';
   
           String createLogEntry(
  +          String message,
  +          LogSeverity severity, {
  +          Frame stackFrame,
  +        }) {
  +          // https://cloud.google.com/logging/docs/agent/configuration#special-fields
  +          final logContent = {
  +            'message': message,
  +            'severity': severity,
  +            // 'logging.googleapis.com/labels': { }
  +            if (traceHeader != null)
  +              'logging.googleapis.com/trace': traceValue(),
  +            if (stackFrame != null)
  +              'logging.googleapis.com/sourceLocation':
  +                  _sourceLocation(stackFrame),
  +          };
  +          return jsonEncode(logContent);
  +        }
  +
  +        String createErrorLogEntry(
             Object error,
             StackTrace stackTrace,
             LogSeverity logSeverity, {
  
positive.code: 
            final stackFrame = _frameFromChain(chain);
  
            // https://cloud.google.com/logging/docs/agent/configuration#special-fields
            final logContent = {
              'message': '$error\n$chain'.trim(),
              'severity': logSeverity,
              // 'logging.googleapis.com/labels': { }
              if (traceHeader != null)
                'logging.googleapis.com/trace': traceValue(),
              if (stackFrame != null)
                'logging.googleapis.com/sourceLocation':
                    _sourceLocation(stackFrame),
            };
  
            return jsonEncode(logContent);
          }
  
          final completer = Completer<Response>.sync();
  
negative.code:               completer.complete(response);
              },
              print: (self, parent, zone, line) {
                final logContent = createLogEntry(line, LogSeverity.info);
  
                // Serialize to a JSON string and output to parent zone.
                parent.print(self, logContent);
              },
            ),
          )
  