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

// istanbul since its catching a race condition.
      /* istanbul ignore if */
      if (err && err.status && err.status === 412) {
        return true;
      }
      return Promise.reject(err);
    });

    setupPromise.catch(function () {
      setupPromise = null;
    });

    return setupPromise;
  }

  nextTick(function () {
    callback(null, api);
  });

  api._remote = true;

  /* istanbul ignore next */
  api.type = function () {
    return 'http';
  };

  api.id = adapterFun('id', function (callback) {
    ourFetch(genUrl(host, '')).then(function (response) {
      return response.json();
    }).catch(function () {
      return {};
    }).then(function (result) {

function complete(err) {
      /* istanbul ignore if */
      if (err) {
        return nextTick(function () {
          callback(err);
        });
      }
      txn.batch([
        {
          prefix: stores.metaStore,
          type: 'put',
          key: UPDATE_SEQ_KEY,
          value: newUpdateSeq
        },
        {
          prefix: stores.metaStore,
          type: 'put',
          key: DOC_COUNT_KEY,
          value: db._docCount + docCountDelta
        }

if (returnValue.cancelled) {
      return completeReplication();
    }
    // Attach 'pending' property if server supports it (CouchDB 2.0+)
    /* istanbul ignore if */
    if (typeof pending === 'number') {
      pendingBatch.pending = pending;
    }

    var filter = filterChange(opts)(change);
    if (!filter) {
      return;
    }
    pendingBatch.seq = change.seq || lastSeq;
    pendingBatch.changes.push(change);
    nextTick(function () {
      processPendingBatch(batches.length === 0 && changesOpts.live);
    });
  }

openReqList.delete(dbName);
      if (hasLocalStorage() && (dbName in localStorage)) {
        delete localStorage[dbName];
      }
      callback(null, { 'ok': true });
    };

    req.onerror = idbError(callback);
  };

  var cached = cachedDBs.get(dbName);

  if (cached) {
    idb = cached.idb;
    api._meta = cached.global;
    return nextTick(function () {
      callback(null, api);
    });
  }

  var req = indexedDB.open(dbName, ADAPTER_VERSION);
  openReqList.set(dbName, req);

  req.onupgradeneeded = function (e) {
    var db = e.target.result;
    if (e.oldVersion < 1) {
      return createSchema(db); // new db, initial schema
    }
    // do migrations

    var txn = e.currentTarget.transaction;
    // these migrations have to be done in this function, before

return getArguments(function (args) {
      db._queue.push({
        fun: fun,
        args: args,
        type: 'read'
      });

      if (db._queue.length === 1) {
        nextTick(executeNext);
      }
    });
  }