def _font_stretch(stretch):
    """Return a suitable font stretch."""
    if isinstance(stretch, str):
        return {'ultra-condensed': 50, 'extra-condensed': 62, 'condensed': 
            75, 'semi-condensed': 87, 'normal': 100, 'semi-expanded': 112,
            'expanded': 125, 'extra-expanded': 150, 'ultra-expanded': 200}.get(
            stretch, 100)
    return int(stretch)
