constants.py

entity_unit_map = {
    'width': {'centimetre', 'foot', 'inch', 'metre', 'millimetre', 'yard'},
    'depth': {'centimetre', 'foot', 'inch', 'metre', 'millimetre', 'yard'},
    'height': {'centimetre', 'foot', 'inch', 'metre', 'millimetre', 'yard'},
    'item_weight': {'gram',
        'kilogram',
        'microgram',
        'milligram',
        'ounce',
        'pound',
        'ton'},
    'maximum_weight_recommendation': {'gram',
        'kilogram',
        'microgram',
        'milligram',
        'ounce',
        'pound',
        'ton'},
    'voltage': {'kilovolt', 'millivolt', 'volt'},
    'wattage': {'kilowatt', 'watt'},
    'item_volume': {'centilitre',
        'cubic foot',
        'cubic inch',
        'cup',
        'decilitre',
        'fluid ounce',
        'gallon',
        'imperial gallon',
        'litre',
        'microlitre',
        'millilitre',
        'pint',
        'quart'}
}

allowed_units = {unit for entity in entity_unit_map for unit in entity_unit_map[entity]}