function isSnapped(event, axis) {
  var snapped = event.snapped;

  if (!snapped) {
    return false;
  }

  if (typeof axis === 'string') {
    return snapped[axis];
  }

  return snapped.x && snapped.y;
}
Retrieve the snap state of the given event.

@param {Event} event
@param {Axis} axis

@return {boolean} the snapped state