Hopper Filter

A slot for item('s) that allow the player to place an item that the hopper will accept. I would suggest 1-5 item slots above the existing slots that allow a filter. For example: placing a cobble stone block in the filter would hold an item until removed. While the item is in the filter spot the hopper will only accept an item of the same type. This would greatly improve the experience of the Minecraft game and make it easier to build redstone contraptions for farms. More casual players would have fun too.