drywet(fade) {
    if (typeof fade !== 'undefined') {
      this._drywet.fade.value = fade;
    }
    return this._drywet.fade.value;
  }
Adjust the dry/wet value.

 @method drywet
 @for p5.Effect
 @param {Number} [fade] The desired drywet value (0 - 1.0)