def font_stretch(keyword):
    """Validation for the ``font-stretch`` property."""
    return keyword in (
        'ultra-condensed', 'extra-condensed', 'condensed', 'semi-condensed',
        'normal',
        'semi-expanded', 'expanded', 'extra-expanded', 'ultra-expanded')
Validation for the ``font-stretch`` property.
weasyprint/css/validation/properties.py