Final call not possible

[henit]

Hi,

I am using bem-cn 3.0.1. I need to get class names as strings, but when I am trying to follow this instruction:

Use final call without arguments to get a string

<CustomComponent className={b('icon')()} />

It complains that b('icon') is not a function. Example code:

import { block } from 'bem-cn';

const b = block('button');

console.info(typeof b('icon'), b('icon'));
console.info(typeof b('icon')(), b('icon')());

Console result:

object {mix: ƒ, split: ƒ, is: ƒ, has: ƒ, state: ƒ, …}
Uncaught TypeError: b(...) is not a function

The object contains toString, so b('icon').toString() works, but to simplify syntax, I was hoping to be able to run the final call from the docs.