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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 _coord(sequence, start, mirna, precursor, iso):
 """ Define t5 and t3 isomirs """

    dif = abs(mirna[0] - start)
    if start < mirna[0]:
        iso.t5 = sequence[:dif].upper()
    elif start > mirna[0]:
        iso.t5 = precursor[mirna[0] - 1:mirna[0] - 1 + dif].lower()
    elif start == mirna[0]:
        iso.t5 = "NA"
    if dif > 4:
        logger.debug("start > 3 %s %s %s %s %s" % (start, len(sequence), dif, mirna, iso.format()))
        return None

    end = start + (len(sequence) - len(iso.add)) - 1
    dif = abs(mirna[1] - end)
    if iso.add:
        sequence = sequence[:-len(iso.add)]
    # if dif > 3:
    #    return None
    if end > mirna[1]:
        iso.t3 = sequence[-dif:].upper()
    elif end < mirna[1]:
        iso.t3 = precursor[mirna[1] - dif:mirna[1]].lower()
    elif end == mirna[1]:
        iso.t3 = "NA"
    if dif > 4:
        logger.debug("end > 3 %s %s %s %s %s" % (len(sequence), end, dif, mirna, iso.format()))
        return None
    logger.debug("%s %s %s %s %s %s" % (start, len(sequence), end, dif, mirna, iso.format()))
    return True