def get_bases_at_site(alignment_obj, chromosome, position):
    """

    So to convert INS from 0 to 1-based system:
    start = start + 1; end = end + 1
    and to convert INS from 1 to 0-based system:
    start = start - 1; end = end - 1

    :param alignment_obj:
    :param chromosome:
    :param position:
    :return:
    """
    position = int(position)
    read_list = alignment_obj.pileup(chromosome, position, position + 1)
    base_list = []
    for pileupcolumn in read_list:
        if pileupcolumn.pos == position:
            for pileupread in pileupcolumn.pileups:
                if not pileupread.is_del and not pileupread.is_refskip:
                    base_list.append(pileupread.alignment.query_sequence[
                        pileupread.query_position])
    return base_list
