code: def stack(self, output):
      return tf.stack(output)
  
file_path: BigDL/python/nano/src/bigdl/nano/deps/openvino/tf/metric.py
imports: import tensorflow
  from tensorflow.keras.metrics import Metric
  from bigdl.nano.utils.common import invalidInputError
  from ..core.metric import BaseOpenVINOMetric
label_desc: Use image node_id 2 for calling the KerasOpenVINOMetric obj's underlying member method code with example usage: obj.stack(output) and returns: tf