 Adafruit_Simple_AHRS ahrs(&lsm.getAccel(), &lsm.getMag());
  
 float pos = 6;  // Starting center position of pupil
-float increment = 2 * 3.14159 / 21; // distance between pixels in radians
+float increment = 2 * 3.14159 / NUM_PIXELS; // distance between pixels in radians
 float MomentumH = 0; // horizontal component of pupil rotational inertia
 float MomentumV = 0; // vertical component of pupil rotational inertia
 

// utility function for feedback on mode changes.
void spin(CRGB color, int count, int time) {
  for (int j = 0; j < count; j++) {
    for (int i = 0; i < 21; i++) {
      rightLense[i] = color;
      leftLense[i] = color;
      FastLED.show();
      delay(max(time / 21, 1));
      leftLense[i] = CRGB::Black;
      rightLense[i] = CRGB::Black;
      FastLED.show();


// Reset to default
void resetModes() {
   antiGravity = false;
   mirroredEyes = false;
   
   /// spin-up
