void add(IPropagationPart part, @Nullable IPropagationPart from, int mode) {
            if (from != lastCaller) {
                lastCaller = from;
                count++;
            }
            propagationTasks.add(() -> part.updateAndPropagate(from, mode));
        }
Used when the propagator did not change signal, but a new connection may
have been established and signal needs recalculating
core/src/main/java/mrtjp/projectred/core/RedstonePropagator.java