VS.trichords = [
  [0, 1, 2],
  [0, 1, 3],
  [0, 1, 4],
  [0, 1, 5],
  [0, 1, 6],
  [0, 2, 4],
  [0, 2, 5],
  [0, 2, 6],
  [0, 2, 7],
  [0, 3, 6],
  [0, 3, 7],
  [0, 4, 8],
];