message: A class, I say!
diff: @@ -214,7 +214,8 @@ std::string AbslUnparseFlag(const AlignmentPolicy& policy);
  // This represents one unit of alignable work, which is usually a filtered
  // subset of partitions within a contiguous range of partitions.
  -struct AlignablePartitionGroup {
  +class AlignablePartitionGroup {
  + public:
  AlignablePartitionGroup(const std::vector<TokenPartitionIterator>& rows,
  const AlignmentCellScannerFunction& scanner,
  AlignmentPolicy policy)
  