class_docstr: Defines the interface for TF metrics.
docstr: Computes and returns a final value for the metric.
docstr_tok: ["Computes","and","returns","a","final","value","for","the","metric","."]
code: def result(self):
      """Computes and returns a final value for the metric."""
      raise NotImplementedError(
          "Metrics must define a result() member function"
      )
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  import tensorflow
  from tf_agents.utils import common
label_desc: Use image node_id 4 for calling the TFStepMetric obj's underlying member method code with example usage: obj.result() without return types