def _nrange_locs(cnf_locs, nthresh, ignore_locs_lst=()):
    """ Obtain a list of up-to N conformer locators where N is the
        number requested by the user. The count (N=1) begins from the
        minimum-energy conformer.

        :param cnf_locs: (ring-id, tors-id) CONF filesys locators
        :type cnf_locs: tuple(tuple(str), tuple(str))
        :rtype: tuple(str)
    """

    thresh = int(nthresh.split('n')[1])

    min_cnf_locs = []
    idx = 0
    for locs in cnf_locs:
        if locs not in ignore_locs_lst:
            if idx+1 <= thresh:
                min_cnf_locs.append(locs)
            idx += 1

    return min_cnf_locs