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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 experiment_pb( hparam_infos, metric_infos, user='', description='', time_created_secs=None):
 """Creates a summary that defines a hyperparameter-tuning experiment. Args: hparam_infos: Array of api_pb2.HParamInfo messages. Describes the hyperparameters used in the experiment. metric_infos: Array of api_pb2.MetricInfo messages. Describes the metrics used in the experiment. See the documentation at the top of this file for how to populate this. user: String. An id for the user running the experiment description: String. A description for the experiment. May contain markdown. time_created_secs: float. The time the experiment is created in seconds since the UNIX epoch. If None uses the current time. Returns: A summary protobuffer containing the experiment definition. """

  if time_created_secs is None:
    time_created_secs = time.time()
  experiment = api_pb2.Experiment(
      description=description,
      user=user,
      time_created_secs=time_created_secs,
      hparam_infos=hparam_infos,
      metric_infos=metric_infos)
  return _summary(metadata.EXPERIMENT_TAG,
                  plugin_data_pb2.HParamsPluginData(experiment=experiment))