def fetch_deletion(chrom, st, cigar):
    """ fetch deletion regions defined by cigar. st must be zero based
	return list of tuple of (chrom,st, end)
	"""
    chrom_st = st
    del_bound = []
    for c, s in cigar:
        if c == 0:
            chrom_st += s
        elif c == 1:
            continue
        elif c == 2:
            del_bound.append((chrom, chrom_st, chrom_st + s))
            chrom_st += s
        elif c == 3:
            chrom_st += s
        elif c == 4:
            chrom_st += s
        else:
            continue
    return del_bound
