prolounged redstone signal block

This block has 3 distinct sides, the input on the back, the pass activator on either side, and the output in the front.

the input changes the blocks value to a certain signal strength, unless that input is zero. for example you can set the block to strenght 3, then to 5, then back to 3, but when the redstone signal strenght goes to zero, the block retains the number 3.

the pass activator allows the retained value of the block to be sent out on the output side.

the output is where the retained strenght of the block is sent out after being activated, and if a signal is sent into the output side while the pass activator isn't on, then the retained value is deleted.