How to use proxy?

Hey, I have a proxy (cnltm)，and the proxy is: 192.0.0.2:3128，it do not have username
and user passwd

But when I use s4cmd，It always print error like this:

[Exception] An error occurred (407) when calling the PutObject operation: Proxy Authentication Required
[Thread Failure] An error occurred (407) when calling the PutObject operation: Proxy Authentication Required

I have add some code to use proxy:

from botocore.config import Config as botoconfig


Start by reproducing the PutObject request with the supplied botocore Config proxy settings and inspect how s4cmd passes proxy configuration to botocore. Done means establishing whether an unauthenticated proxy is supported and documenting or correcting the behavior behind the HTTP 407 response.

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