appendMetric = function appendMetric(outputIndex, metricName, metricTensor) {
	      if (_this2.outputNames.length > 1) {
	        metricName = _this2.outputNames[outputIndex] + '_' + metricName;
	      }

	      _this2.metricsNames.push(metricName);

	      _this2.metricsTensors.push([metricTensor, outputIndex]);
	    }
Helper function used in loop below.