def save_ds9(output, filename):
    """Save ds9 region output info filename.

    Parameters
    ----------
    output : str
        String containing the full output to be exported as a ds9 region
        file.
    filename : str
        Output file name.

    """

    ds9_file = open(filename, 'wt')
    ds9_file.write(output)
    ds9_file.close()