[virtual-signal=signal-1] From "Sub-tree merge", we have this 3:2 ratio splitter. [virtual-signal=signal-2] If we feed the empty input with a belt, then all the emptiness would be filled, and the output becomes two full belts. [virtual-signal=signal-3] The rectangle can also be "uncompleted". Removing the original input belt creates a new 3:2 ratio splitter.