function cloneTransform(input, output) {
  if (output !== undefined) {
    for (let i = 0, ii = input.length; i < ii; ++i) {
      output[i] = input[i];
    }
    output = output;
  } else {
    output = input.slice();
  }
  return output;
}
@param {Array<number>} input Input coordinate array.
@param {Array<number>} [output] Output array of coordinate values.
@return {Array<number>} Output coordinate array (new array, same coordinate
    values).