Proxy gateways do not run workers, and are meant to be passed with the
`via` attribute to additional gateways.
They are useful for running multiple workers on remote machines.
Example usage:
```
pytest -sv --dist=load --px "id=my_proxy//socket=IP:PORT" --tx "5*popen//via=my_proxy"
```
Proxy gateways do not run workers, anda re meant to be passed
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