How to use the pouchdb-merge.isDeleted function in pouchdb-merge

txn.objectStore(DOC_STORE).get(id).onsuccess = function (e) {
      metadata = decodeMetadata(e.target.result);
      // we can determine the result here if:
      // 1. there is no such document
      // 2. the document is deleted and we don't ask about specific rev
      // When we ask with opts.rev we expect the answer to be either
      // doc (possibly with _deleted=true) or missing error
      if (!metadata) {
        err = createError(MISSING_DOC, 'missing');
        return finish();
      }

      var rev;
      if (!opts.rev) {
        rev = metadata.winningRev;
        var deleted = isDeleted(metadata);
        if (deleted) {
          err = createError(MISSING_DOC, "deleted");
          return finish();
        }
      } else {
        rev = opts.latest ? getLatest(opts.rev, metadata) : opts.rev;
      }

      var objectStore = txn.objectStore(BY_SEQ_STORE);
      var key = metadata.id + '::' + rev;

      objectStore.index('_doc_id_rev').get(key).onsuccess = function (e) {
        doc = e.target.result;
        if (doc) {
          doc = decodeDoc(doc);
        }

function insertDoc(docInfo, resultsIdx, callback) {
    // Cant insert new deleted documents
    var winningRev = calculateWinningRev(docInfo.metadata);
    var deleted = isDeleted(docInfo.metadata, winningRev);
    if ('was_delete' in opts && deleted) {
      results[resultsIdx] = createError(MISSING_DOC, 'deleted');
      return callback();
    }

    // 4712 - detect whether a new document was inserted with a _rev
    var inConflict = newEdits && rootIsMissing(docInfo);

    if (inConflict) {
      var err = createError(REV_CONFLICT);
      results[resultsIdx] = err;
      return callback();
    }

    var delta = deleted ? 0 : 1;

if (err) {
      return cb(err);
    }

    var doc = result.doc;
    var metadata = result.metadata;
    var ctx = result.ctx;

    if (opts.conflicts) {
      var conflicts = collectConflicts(metadata);
      if (conflicts.length) {
        doc._conflicts = conflicts;
      }
    }

    if (isDeleted(metadata, doc._rev)) {
      doc._deleted = true;
    }

    if (opts.revs || opts.revs_info) {
      var splittedRev = doc._rev.split('-');
      var revNo       = parseInt(splittedRev[0], 10);
      var revHash     = splittedRev[1];

      var paths = rootToLeaf(metadata.rev_tree);
      var path = null;

      for (var i = 0; i < paths.length; i++) {
        var currentPath = paths[i];
        var hashIndex = currentPath.ids.map(function (x) { return x.id; })
          .indexOf(revHash);
        var hashFoundAtRevPos = hashIndex === (revNo - 1);

err.docId = id;
      return cb(err);
    }

    var doc = result.doc;
    var metadata = result.metadata;
    var ctx = result.ctx;

    if (opts.conflicts) {
      var conflicts = collectConflicts(metadata);
      if (conflicts.length) {
        doc._conflicts = conflicts;
      }
    }

    if (isDeleted(metadata, doc._rev)) {
      doc._deleted = true;
    }

    if (opts.revs || opts.revs_info) {
      var splittedRev = doc._rev.split('-');
      var revNo       = parseInt(splittedRev[0], 10);
      var revHash     = splittedRev[1];

      var paths = rootToLeaf(metadata.rev_tree);
      var path = null;

      for (var i = 0; i < paths.length; i++) {
        var currentPath = paths[i];
        var hashIndex = currentPath.ids.map(function (x) { return x.id; })
          .indexOf(revHash);
        var hashFoundAtRevPos = hashIndex === (revNo - 1);

docStore.openCursor().onsuccess = function (event) {
      var cursor = event.target.result;
      if (cursor) {
        var metadata = cursor.value;
        var deleted = isDeleted(metadata);
        metadata.deletedOrLocal = deleted ? "1" : "0";
        docStore.put(metadata);
        cursor.continue();
      } else {
        callback();
      }
    };
  }

function processChange(doc, metadata, opts) {
  var changeList = [{rev: doc._rev}];
  if (opts.style === 'all_docs') {
    changeList = collectLeaves(metadata.rev_tree)
    .map(function (x) { return {rev: x.rev}; });
  }
  var change = {
    id: metadata.id,
    changes: changeList,
    doc: doc
  };

  if (isDeleted(metadata, doc._rev)) {
    change.deleted = true;
  }
  if (opts.conflicts) {
    change.doc._conflicts = collectConflicts(metadata);
    if (!change.doc._conflicts.length) {
      delete change.doc._conflicts;
    }
  }
  return change;
}