code: def _compute_mean_metric(pipeline, computation):
      return (
          pipeline
          | "Create" >> beam.Create(_get_examples())
          | "Process" >> beam.Map(metric_util.to_standard_metric_inputs)
          | "AddSlice" >> beam.Map(lambda x: ((), x))
          | "ComputeMeanMetric"
          >> beam.CombinePerKey(computation.combiner)
      )
  
imports: from absl.testing import parameterized
  import apache_beam
  from apache_beam.testing import util
  import numpy
  import tensorflow
  import tensorflow_model_analysis
  from tensorflow_model_analysis.eval_saved_model import testutil
  from tensorflow_model_analysis.metrics import metric_types
  from tensorflow_model_analysis.metrics import metric_util
  from tensorflow_model_analysis.metrics import stats
  from google.protobuf import text_format
label_desc: Use image node_id 2 for calling a global function with example usage: _compute_mean_metric(pipeline, computation) and returns: unknown