docs: private int seekRow(final long timestamp) {
      checkRowOrder();
      int row_index = 0;
      iRowSeq row = null;
      final int nrows = rows.size();
      for (int i = 0; i < nrows; i++) {
        row = rows.get(i);
        final int sz = row.size();
        if (sz < 1) {
          row_index++;
        } else if (row.timestamp(sz - 1) < timestamp) {
          row_index++;  // The last DP in this row is before 'timestamp'.
        } else {
          break;
        }
      }
      if (row_index == nrows) {  // If this timestamp was too large for the
        --row_index;             // last row, return the last row.
      }
      return row_index;
    }