function translation(xOffset, yOffset) {
  return (onRefs, onOffsets, offOffsets) => {
    const translatedOnRefs = onRefs.map(
      pt => [ pt[0] + xOffset, pt[1] + yOffset ]);
    return [ translatedOnRefs, onOffsets, offOffsets ];
  }
}
Translation
@param { number } xOffset
@param { number } yOffset
@returns { Filter }