code: function oscillate(t, b, c, d) {
    var i = 4;            // # of bounces
    t /= d;               // percentage
    t = Math.PI * i * t;  // go from 0 -> 2π
    t = Math.sin(t) * c;  // now, oscillates between c, -c
    t = Math.abs(t);      // "half wave rectifier"
    return t + b;
  }
docs: /*eslint max-len: ["error", 120]