Failing enum-based API Blueprint

out.txt

{ code: 1,
  message: 'parser exception: \'mismatched adapter and node type\'',
  location: [] }

test.js

var protagonist = require('protagonist');

test = (
    "# Data Structures\n" +
    "## TimeUnit (enum[string])\n" +
    "+ Members\n" +
    "    + `hello`"
);

protagonist.parse(test, function(error, result) {
    if (error) {
        console.log(error);
        return;
    }

    console.log(result);
});

# Data Structures

## TimeUnit (enum[string])
### Members
- hello