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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 _get_prep_params(data):
 """Retrieve configuration parameters with defaults for preparing BAM files. """

    realign_param = dd.get_realign(data)
    realign_param = "gatk" if realign_param is True else realign_param
    return {"realign": realign_param}