Run-time permissions status using diagnostic plugin

I am building an app targeting API v23 and I need to ask the user for the permission at run-time.

I am using the docs on this page http://ionicframework.com/docs/v2/native/diagnostic/

It states that one of the static methods is getPermissionAuthorizationStatus. But when I

import {Diagnostic} from 'ionic-native'

and try calling the method

Diagnostic.getPermissionAuthorizationStatus()

it shows an error because it is not defined in the diagnostic.d.ts file.

What should I do now? Thanks.