clone() {
    const clone = new shaka.text.Cue(0, 0, '');

    for (const k in this) {
      clone[k] = this[k];

      // Make copies of array fields, but only one level deep.  That way, if we
      // change, for instance, textDecoration on the clone, we don't affect the
      // original.
      if (Array.isArray(clone[k])) {
        clone[k] = /** @type {!Array} */(clone[k]).slice();
      }
    }

    return clone;
  }
Create a copy of the cue with the same properties.
@return {!shaka.text.Cue}
@suppress {checkTypes} since we must use [] and "in" with a struct type.
@export