code: def remove(self, pk):
          
          pk = str(pk)
          try:
              del self.items[pk]
          except KeyError:
              raise ItemNotInCart(pk=pk)
          self.update()
docs: Remove an item from the cart.
  
          Parameters
          ----------
          pk : str or int
              The primary key of the item.
  
          Raises
          ------
          ItemNotInCart