def bin_names_to_coords_filepath(query_bin, ref_bin, results_dir):
    """
    prepare a file path for results
    :param query_bin: bin number 1 name/filepath (reference sequence)
    :param ref_bin: bin number 2 name/filepath.  (query sequence)
    :return:string like Acidovora-69x_Ga0081644_to_Acidovorax-79_Ga0081651
    """
    return results_dir + '/' + query_bin + "_to_" + ref_bin