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void draw() {
  background(204);
  int s = second();  // Values from 0 - 59
  int m = minute();  // Values from 0 - 59
  int h = hour();    // Values from 0 - 23
  line(s, 0, s, 33);
  line(m, 33, m, 66);
  line(h, 66, h, 100);
}

hour()