Not able to use any methods of the pouch db

[AKASH PATEL]

Using pouch db in angular 4

import * as  PouchDB from 'pouchdb'

connectCandidateDb() {

const db = new PouchDB('candidate');

return db;

}

let userDb = this.pouchService.connectUsersDb;

userDb.allDocs() gives  in [at-loader] ./ClientApp/app/components/newCandidate/newCandidate.component.ts:98:10

TS2339: Property 'allDocs' does not exist on type '() => Database<{}>'.