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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 to_input_req(self):
 """Converts the ``self`` instance to the desired input request format. Returns: dict: Containing the "WarmStartType" and "ParentHyperParameterTuningJobs" as the first class fields. Examples: { "WarmStartType":"TransferLearning", "ParentHyperParameterTuningJobs": [ {'HyperParameterTuningJobName': "p1"}, {'HyperParameterTuningJobName': "p2"}, ] } """

        return {
            WARM_START_TYPE: self.type.value,
            PARENT_HYPERPARAMETER_TUNING_JOBS: [{HYPERPARAMETER_TUNING_JOB_NAME: parent} for parent in self.parents]
        }