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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 reference_preprocessing(job, samples, config):
 """ Spawn the jobs that create index and dict file for reference :param JobFunctionWrappingJob job: passed automatically by Toil :param Namespace config: Argparse Namespace object containing argument inputs :param list[list] samples: A nested list of samples containing sample information """

    job.fileStore.logToMaster('Processed reference files')
    config.fai = job.addChildJobFn(run_samtools_faidx, config.reference).rv()
    config.dict = job.addChildJobFn(run_picard_create_sequence_dictionary, config.reference).rv()
    job.addFollowOnJobFn(map_job, download_sample, samples, config)