Preventing Default Recursive Merge | Not Working

As of today, the helper [library](https://github.com/google/data-layer-helper/blob/master/dist/data-layer-helper.js) is not responding to the "_clear " attribute passed into the data layer array.

**Existing Value** --- {a: {x: undefined, y: 2}}
**New Value** --- {a: {x: 1}, _clear: true}
**Expected Result** --- {a: {x: 1}} (as per documentation)
**Actual Result** --- {a: {x: 1, y: 2}}

Kindly look into this or remove this feature from the readme file