How to use the pouchdb-mapreduce-utils.uniq function in pouchdb-mapreduce-utils

}
      var newKeys = mapToKeysArray(indexableKeysToKeyValues);
      newKeys.forEach(function (key) {
        if (!oldKeys.has(key)) {
          // new doc
          var kvDoc = {
            _id: key
          };
          var keyValue = indexableKeysToKeyValues.get(key);
          if ('value' in keyValue) {
            kvDoc.value = keyValue.value;
          }
          kvDocs.push(kvDoc);
        }
      });
      metaDoc.keys = uniq(newKeys.concat(metaDoc.keys));
      kvDocs.push(metaDoc);

      return kvDocs;
    }

var finalResults;
      if (shouldReduce) {
        finalResults = reduceView(view, rows, opts);
      } else {
        finalResults = {
          total_rows: totalRows,
          offset: skip,
          rows: rows
        };
      }
      /* istanbul ignore if */
      if (opts.update_seq) {
        finalResults.update_seq = view.seq;
      }
      if (opts.include_docs) {
        var docIds = uniq(rows.map(rowToDocId));

        return view.sourceDB.allDocs({
          keys: docIds,
          include_docs: true,
          conflicts: opts.conflicts,
          attachments: opts.attachments,
          binary: opts.binary
        }).then(function (allDocsRes) {
          var docIdsToDocs = new Map();
          allDocsRes.rows.forEach(function (row) {
            docIdsToDocs.set(row.id, row.doc);
          });
          rows.forEach(function (row) {
            var docId = rowToDocId(row);
            var doc = docIdsToDocs.get(docId);
            if (doc) {