positionX(xVal, time) {
    var t = time || 0;
    if (typeof xVal === 'number') {
      this.panner.positionX.value = xVal;
      this.panner.positionX.cancelScheduledValues(
        this.ac.currentTime + 0.01 + t
      );
      this.panner.positionX.linearRampToValueAtTime(
        xVal,
        this.ac.currentTime + 0.02 + t
      );
    } else if (xVal) {
      xVal.connect(this.panner.positionX);
    }
    return this.panner.positionX.value;
  }
Getter and setter methods for position coordinates
@method positionZ
@for p5.Panner3D
@return {Number}      updated coordinate value