text: from django import template
  from django_prices.templatetags.prices_i18n import gross
  from prices import Price
  
  register = template.Library()
  
  
  @register.simple_tag
  def discount_as_negative(discount, html=False):
      zero = Price(0, currency=discount.amount.currency)
      return gross(zero-discount.amount, html=html)
  