import collections


def _create_gt_string(cnv_row):
    """
        Creates VCF gt string for a single-sample VCF.
    """
    gt_dict = collections.OrderedDict()
    gt_dict["GT"] = cnv_row.GT
    gt_dict["S"] = cnv_row.S
    gt_dict["NS"] = cnv_row.NS
    gt_dict["LS"] = cnv_row.LS
    gt_dict["LNS"] = cnv_row.LNS
    gt_dict["RS"] = cnv_row.RS
    gt_dict["RNS"] = cnv_row.RNS
    gt_dict["GQ"] = cnv_row.GQ
    gt_dict["AB"] = cnv_row.AB
    gt_dict["SQ"] = cnv_row.SQ
    out_string = "" 
    length_of_info = len(gt_dict.values())
    for i, item in enumerate(gt_dict.items()):
        value = str(item[1])
        if (i + 1) != length_of_info:
            out_string += value +":"
        else:
            out_string += value 
    return out_string