docs: function quadratic2cubicBezier (a, b) {
    return [
      [
        (a / 3 + (a + b) / 3 - a) / (b - a),
        (a * a / 3 + a * b * 2 / 3 - a * a) / (b * b - a * a)
      ], [
        (b / 3 + (a + b) / 3 - a) / (b - a),
        (b * b / 3 + a * b * 2 / 3 - a * a) / (b * b - a * a)
      ]
    ]
  }