code: func OptImportSort(sorting bool) ImportOption {
  	return func(options *ImportOptions) error {
  		// skipSort is expressed negatively because we want to
  		// keep sorting enabled by default, so the zero value should
  		// be that default behavior. The client option expresses it
  		// positively because that's easier for API users.
  		options.skipSort = !sorting
  		return nil
  	}
  }
docs: // OptImportSort tells the importer whether or not to sort batches of records, on
  // by default. Sorting imposes some performance cost, especially on data that's
  // already sorted, but dramatically improves performance in pathological
  // cases. It is enabled by default because the pathological cases are awful,
  // and the performance hit is comparatively small, but the performance cost can
  // be significant if you know your data is sorted.