   if (0<Serial.available()) {
     String command = Serial.readStringUntil(':');
     String argument = Serial.readStringUntil(';');
+    
     if(command=="i") { // set instrument color
       Serial.println(command);
       if(argument.length()==11) {

    }
    else if(command=="s") { // sound trigger
      brightness = 1.0;
    }
    else {
      Serial.print("Command not found: ");

}

void updateLED() {
  Serial.println("updateLED");
  uint32_t instrument_color = multiplicateBrightness(i_color_r, i_color_g, i_color_b);
  uint32_t effect_color = multiplicateBrightness(e_color_r, e_color_g, e_color_b);

  float unit = (float) TOTAL_PIXELS / (float) divide;
  int unit_number = 1;
  int unit_start = 0;
  for(uint16_t i=0; i<TOTAL_PIXELS;) {
    if(i<unit*unit_number){
      if(i<unit_start+unit*slit_position) {
        strip.setPixelColor(i, instrument_color);
      }
      else {
        strip.setPixelColor(i, effect_color);
      }
      i++;
    }
    else {
      unit_number++;
      unit_start = i;
    }
  }
  strip.show();
