def find_uts_hlines(ndvar):
    """Find horizontal lines for uts plots (based on contours)

    Parameters
    ----------
    ndvar : NDVar
        Data to be plotted.

    Returns
    -------
    h_lines : iterator
        Iterator over (y, kwa) tuples.
    """
    contours = ndvar.info.get('contours', None)
    if contours:
        for level in sorted(contours):
            args = contours[level]
            if isinstance(args, dict):
                yield level, args.copy()
            else:
                yield level, {'color': args}
