title: What is the usage of the flag '--use_env' while parsing some command line arguments in python?
body: <p>I am referring a git repository which uses following bash file for starting the training of a neural network. I want to understand the use of '--use_env' flag.</p>
  <pre><code>#! /bin/bash
  CUDA_VISIBLE_DEVICES=2 python -m torch.distributed.launch --nproc_per_node=1 --master_port 2351 --use_env train.py --dataroot SOME_PATH_TO_DATA
  </code></pre>
  <p>In the above command, what is the importance of '--use_env' flag? I have also checked that if I remove that flag, I get error saying &quot;train.py: error: unrecognized arguments: -m torch.distributed.launch&quot; as shown below.</p>
  <pre><code>train.py: error: unrecognized arguments: -m torch.distributed.launch
  </code></pre>
  <p>I am not able to find any relevant resources to know more about these flags. Could anyone please help me understand the use of this flag or suggest any resources to refer to?</p>