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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 run(self):
 """Executes the request. Returns: An array of tuples representing the metric evaluations--each of the form (<wall time in secs>, <training step>, <metric value>). """

    run, tag = metrics.run_tag_from_session_and_metric(
        self._request.session_name, self._request.metric_name)
    body, _ = self._scalars_plugin_instance.scalars_impl(
        tag, run, None, scalars_plugin.OutputFormat.JSON)
    return body