Cannot find methods of Tokenizer

[Thefolle]

Context

Bug fix?

I cannot call the member functions of Tokenizer, even if I follow the examples on the README.

Current v Expected Results

I should be able to call functions like tokenize. They are declared in _createClass, but how can I access them?
I would like to use even the basic function tokenize.

Repro Steps

1. let lexr = require('lexr/dist/index');
2. let jsLexer = new lexr.Tokenizer("Javascript")