behave: error: format=cucumber_json:PrettyCucumberJSONFormatter is unknown

I am trying to implement: https://docs.getxray.app/display/XRAY/Testing+using+Behave+in+Python

It's generating a report in cucumber format for Xray test management tool.

But on running command:

behave --format=cucumber_json:PrettyCucumberJSONFormatter -o cucumber.json  --format=json -o behave.json

It's throwing me an error:

behave: error: format=cucumber_json:PrettyCucumberJSONFormatter is unknown

Though according to the documentation of Xray I have placed my cucumber_json.py in my root directory.

My project directory:

behave_example
    - features
        - steps
        - try.py
    - cucumber_json.py
    - __init__.py

You can find cucumber_json.py here: https://docs.getxray.app/display/XRAY/Testing+using+Behave+in+Python

Any help will be appreciated.