// use the FastLED library (someone's pre-written code)
#include <FastLED.h>

// set how many LEDs there are and the data pin.
const int numLeds = 30;
const int ledStripPin = 6;

// this creates an array to reference our LEDs
CRGB leds[numLeds];

void setup() {
  // tells the FastLED code e.g. what LEDs we are using, the data pin
  FastLED.addLeds<NEOPIXEL, ledStripPin>(leds, numLeds);

  // limit the strip's draw to 400mA at 5v
  FastLED.setMaxPowerInVoltsAndMilliamps(5, 400);

  // turns the brightness down (so my eyes don't hurt)
  FastLED.setBrightness(8);

pinMode(2, INPUT_PULLUP);
}

void loop() {
    if (digitalRead(2) == LOW) {
      turnAllWhite();
    } else {
      turnAllBlack();
    }
    delay(200);
  }

  void turnAllWhite() {
 for (int light=0; light<30; light++) {
      leds[light] = CRGB::White;
    }
    FastLED.show();
  }

  void turnAllBlack() {
 for (int light=0; light<30; light++) {
      leds[light] = CRGB::Black;
    }
    FastLED.show();
  }