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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 find_existing_split_discordants(data):
 """Check for pre-calculated split reads and discordants done as part of alignment streaming. """

    in_bam = dd.get_align_bam(data)
    sr_file = "%s-sr.bam" % os.path.splitext(in_bam)[0]
    disc_file = "%s-disc.bam" % os.path.splitext(in_bam)[0]
    if utils.file_exists(sr_file) and utils.file_exists(disc_file):
        return sr_file, disc_file
    else:
        sr_file = dd.get_sr_bam(data)
        disc_file = dd.get_disc_bam(data)
        if sr_file and utils.file_exists(sr_file) and disc_file and utils.file_exists(disc_file):
            return sr_file, disc_file
        else:
            return None, None