code: def getVATAmount(self):
          
          has_client_discount = self.aq_parent.getMemberDiscountApplies()
          VATAmount = self.getSubtotalVATAmount()
          if has_client_discount:
              discount = Decimal(self.getDefaultMemberDiscount())
              return Decimal((1 - discount / 100) * VATAmount)
          else:
              return VATAmount
docs: It computes the VAT amount from (subtotal-discount.)*VAT/100, but
          each analysis has its own VAT!
  
          :returns: the analysis request VAT amount with the discount