docs: def add(self, lineitem):
          """
          Add a line item record to this Costs object.
          """
          # Check for a ProductName in the lineitem.
          # If its not there, it is a subtotal line and including it
          # will throw the total cost calculation off.  So ignore it.
          if lineitem['ProductName']:
              self._lineitems.append(lineitem)
              if lineitem['BlendedCost']:
                  self._blended_cost += lineitem['BlendedCost']
              if lineitem['UnBlendedCost']:
                  self._unblended_cost += lineitem['UnBlendedCost']