create temporal normal/tumor bam_file only with reads on that region

def _create_bam_region(paired, region, tmp_dir):
    """create temporal normal/tumor bam_file only with reads on that region"""
    tumor_name, normal_name = paired.tumor_name, paired.normal_name
    normal_bam = _slice_bam(paired.normal_bam, region, tmp_dir, paired.tumor_config)
    tumor_bam = _slice_bam(paired.tumor_bam, region, tmp_dir, paired.tumor_config)
    paired = PairedData(tumor_bam, tumor_name, normal_bam, normal_name, None, None, None)
    return paired