function adaptAttributions(attributionLike) {
  if (!attributionLike) {
    return null;
  }
  if (typeof attributionLike === 'function') {
    return attributionLike;
  }
  if (!Array.isArray(attributionLike)) {
    attributionLike = [attributionLike];
  }
  return (frameState) => attributionLike;
}
Turns the attributions option into an attributions function.
@param {AttributionLike|undefined} attributionLike The attribution option.
@return {Attribution|null} An attribution function (or null).