How to use the pouchdb-utils.clone function in pouchdb-utils

function finishBatch() {
    if (currentBatch.error) {
      throw new Error('There was a problem getting docs.');
    }
    result.last_seq = last_seq = currentBatch.seq;
    var outResult = clone(result);
    if (changedDocs.length) {
      outResult.docs = changedDocs;
      // Attach 'pending' property if server supports it (CouchDB 2.0+)
      /* istanbul ignore if */
      if (typeof currentBatch.pending === 'number') {
        outResult.pending = currentBatch.pending;
        delete currentBatch.pending;
      }
      returnValue.emit('change', outResult);
    }
    writingCheckpoint = true;
    return checkpointer.writeCheckpoint(currentBatch.seq,
        session).then(function () {
      writingCheckpoint = false;
      /* istanbul ignore if */
      if (returnValue.cancelled) {

function LevelPouch(opts, callback) {
  opts = clone(opts);
  var api = this;
  var instanceId;
  var stores = {};
  var revLimit = opts.revs_limit;
  var db;
  var name = opts.name;
  // TODO: this is undocumented and unused probably
  /* istanbul ignore else */
  if (typeof opts.createIfMissing === 'undefined') {
    opts.createIfMissing = true;
  }

  var leveldown = opts.db;

  var dbStore;
  var leveldownName = functionName(leveldown);

function getDocs(src, target, diffs, state) {
  diffs = clone(diffs); // we do not need to modify this

  var resultDocs = [],
      ok = true;

  function getAllDocs() {

    var bulkGetOpts = createBulkGetOpts(diffs);

    if (!bulkGetOpts.docs.length) { // optimization: skip empty requests
      return;
    }

    return src.bulkGet(bulkGetOpts).then(function (bulkGetResponse) {
      /* istanbul ignore if */
      if (state.cancelled) {
        throw new Error('cancelled');

api._allDocs = readLock(function (opts, callback) {
    opts = clone(opts);
    countDocs(function (err, docCount) {
      /* istanbul ignore if */
      if (err) {
        return callback(err);
      }
      var readstreamOpts = {};
      var skip = opts.skip || 0;
      if (opts.startkey) {
        readstreamOpts.gte = opts.startkey;
      }
      if (opts.endkey) {
        readstreamOpts.lte = opts.endkey;
      }
      if (opts.key) {
        readstreamOpts.gte = readstreamOpts.lte = opts.key;
      }

api._allDocs = readLock(function (opts, callback) {
    opts = pouchdbUtils.clone(opts);
    countDocs(function (err, docCount) {
      /* istanbul ignore if */
      if (err) {
        return callback(err);
      }
      var readstreamOpts = {};
      var skip = opts.skip || 0;
      if (opts.startkey) {
        readstreamOpts.gte = opts.startkey;
      }
      if (opts.endkey) {
        readstreamOpts.lte = opts.endkey;
      }
      if (opts.key) {
        readstreamOpts.gte = readstreamOpts.lte = opts.key;
      }

function massageSelector(input) {
  var result = pouchdbUtils.clone(input);
  var wasAnded = false;
  if ('$and' in result) {
    result = mergeAndedSelectors(result['$and']);
    wasAnded = true;
  }

  ['$or', '$nor'].forEach(function (orOrNor) {
    if (orOrNor in result) {
      // message each individual selector
      // e.g. {foo: 'bar'} becomes {foo: {$eq: 'bar'}}
      result[orOrNor].forEach(function (subSelector) {
        var fields = Object.keys(subSelector);
        for (var i = 0; i < fields.length; i++) {
          var field = fields[i];
          var matcher = subSelector[field];
          if (typeof matcher !== 'object' || matcher === null) {

function Changes(db, opts, callback) {
  EE.call(this);
  var self = this;
  this.db = db;
  opts = opts ? clone(opts) : {};
  var complete = opts.complete = once(function (err, resp) {
    if (err) {
      if (listenerCount(self, 'error') > 0) {
        self.emit('error', err);
      }
    } else {
      self.emit('complete', resp);
    }
    self.removeAllListeners();
    db.removeListener('destroyed', onDestroy);
  });
  if (callback) {
    self.on('complete', function (resp) {
      callback(null, resp);
    });
    self.on('error', callback);

.then(function (user) {
    var newUser = clone(user);
    delete newUser._rev;
    newUser._id = USERNAME_PREFIX + newUsername;
    newUser.name = newUsername;
    newUser.roles = opts.roles || user.roles || {};
    return updateUser(newUser, opts).then(function () {
      user._deleted = true;
      return updateUser(user, opts);
    });
  }).then(function (res) {
    callback(null, res);

api._changes = function (opts) {
    opts = clone(opts)

    if (opts.continuous) {
      var id = name + ':' + uuid()
      levelChanges.addListener(name, id, api, opts)
      levelChanges.notify(name)
      return {
        cancel: function () {
          levelChanges.removeListener(name, id)
        }
      }
    }

    var descending = opts.descending
    var results = []
    var lastSeq = opts.since || 0
    var called = 0

api._get = readLock(function (id, opts, callback) {
    opts = clone(opts)

    stores.docStore.get(id, function (err, metadata) {
      if (err || !metadata) {
        return callback(createError(MISSING_DOC, 'missing'))
      }

      var rev = getWinningRev(metadata)
      var deleted = getIsDeleted(metadata, rev)
      if (deleted && !opts.rev) {
        return callback(createError(MISSING_DOC, 'deleted'))
      }

      rev = opts.rev ? opts.rev : rev

      var seq = metadata.rev_map[rev]