def _align(x, y, local = False):
    """
    https://medium.com/towards-data-science/pairwise-sequence-alignment-using-biopython-d1a9d0ba861f
    """
    if local:
        aligned_x = pairwise2.align.localxx(x, y)
    else:
        aligned_x =  pairwise2.align.globalms(x, y, 1, -1, -1, -0.5)
    
    if aligned_x:
        sorted_alignments = sorted(aligned_x, key=operator.itemgetter(2))
        e = enumerate(sorted_alignments[0][0])
        nts = [i for i,c in e if c != "-"]
        return [min(nts), max(nts)]