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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def _set_median_session_metrics(session_group, aggregation_metric):
 """Sets the metrics for session_group to those of its "median session". The median session is the session in session_group with the median value of the metric given by 'aggregation_metric'. The median is taken over the subset of sessions in the group whose 'aggregation_metric' was measured at the largest training step among the sessions in the group. Args: session_group: A SessionGroup protobuffer. aggregation_metric: A MetricName protobuffer. """

  measurements = sorted(_measurements(session_group, aggregation_metric),
                        key=operator.attrgetter('metric_value.value'))
  median_session = measurements[(len(measurements) - 1) // 2].session_index
  del session_group.metric_values[:]
  session_group.metric_values.MergeFrom(
      session_group.sessions[median_session].metric_values)