code: def testInitialize(self):
      mean = metrics.Mean()
      mean.initialize(tf.constant([1.0, 2.0]))
      self.assertAllEqual([1.0, 2.0], mean(tf.constant([1.0, 2.0])))
  
file_path: sonnet/sonnet/src/metrics_test.py
imports: from sonnet.src import metrics
  from sonnet.src import test_utils
  import tensorflow
label_desc: Use image node_id 2 for calling the MeanTest obj's underlying member method code with example usage: obj.testInitialize() without return types