registrasion/templatetags/registrasion_tags.py
def missing_categories(context):
    ''' Adds the categories that the user does not currently have. '''
    user = user_for_context(context)
    categories_available = set(CategoryController.available_categories(user))
    items = ItemController(user).items_pending_or_purchased()

    categories_held = set()

    for product, quantity in items:
        categories_held.add(product.category)

    return categories_available - categories_held
def missing_categories(context):
    ''' Adds the categories that the user does not currently have. '''
    user = user_for_context(context)
    categories_available = set(CategoryController.available_categories(user))
    items = ItemController(user).items_pending_or_purchased()

    categories_held = set()

    for product, quantity in items:
        categories_held.add(product.category)

    return categories_available - categories_held
Adds the categories that the user does not currently have.