def METHOD_NAME(self, prev_ambig_fnames):
    """Get the correct ambiguous restraint names.
    Parameters
    ----------
    prev_ambig_fnames : list
        list of ambig_fname files encoded in previous models
    Returns
    -------
    ambig_fnames : list or None
        list of ambig_fname files to be used by the CNS module
    """
    ambig_fname = self.params["ambig_fname"]
    ambig_fnames = None
    if ambig_fname:
        if ambig_fname.name.endswith("tgz"):
            exp_name = ambig_fname.name.split(".tbl.tgz")[0]
            exp_dir = ambig_fname.parent
            self.log(f"Searching for {exp_name}*tbl files in {exp_dir}")
            path = self.params["ambig_fname"].parent
            ambig_fnames = list(path.glob(f"{exp_name}*tbl"))
            # abort execution if no files are found
            if len(ambig_fnames) == 0:
                raise Exception(
                    f"No {exp_name}*tbl files found in {exp_dir}"
                    )
            self.log(f"Found {len(ambig_fnames)} compatible tbl files")
            ambig_fnames = sort_numbered_paths(*ambig_fnames)
    else:
        if self.params["previous_ambig"]:
            # check if there is restraint information in all models
            if None in prev_ambig_fnames:
                raise Exception("'previous_ambig' option selected but no available restraint information in models")  # noqa: E501
            self.log("Using previously defined restraints")
            ambig_fnames = prev_ambig_fnames.copy()
    return ambig_fnames