Ray Documentation: Use of default_worker.py directly

In Configuring Ray — Ray v1.9.2
it say:

You can also use default_worker.py --temp-dir={your temp path} to start a new worker with the given root temporary directory .

what does it mean “you can use”, is default_worker.py an external api?
can we create our own workers?

Hmm maybe it is the legacy document that wasn’t deleted…