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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_pct(isomirs, mirna):
 """ Get pct of variants respect to the reference using reads and different sequences """

    pass_pos = []
    for isomir in isomirs.iterrows():
        mir = isomir[1]["chrom"]
        mut = isomir[1]["sv"]
        mut_counts = isomir[1]["counts"]
        total = mirna.loc[mir, "counts"] * 1.0 - mut_counts
        mut_diff = isomir[1]["diff"]
        ratio = mut_counts / total
        if mut_counts > 10 and ratio  > 0.4 and mut != "0" and mut_diff > 1:
            isomir[1]["ratio"] = ratio
            pass_pos.append(isomir[1])
    return pass_pos