Proxy option not working

I have this curl request

`curl -x "http://proxy-server.com:8001" -k "https://httpbin.org/ip"`

The curl request is actually going through the proxy server and I'm getting at each hit a new ip address.

But when I try with HTTPoison it's not working as expected.

I tried these codes

`HTTPoison.get!("https://www.httpbin.org/ip", [], [proxy: {"http://proxy-server.com"}])`

`HTTPoison.get!("https://www.httpbin.org/ip", [], [{:proxy, "http://proxy-server.com"}])`

What am I doing wrong ?

Start by reproducing the curl request and the two HTTPoison.get! calls shown in the issue, comparing proxy handling for the HTTPS httpbin.org/ip request. Trace the HTTPoison proxy option behavior and verify completion when the request uses the proxy and produces the expected proxy-visible IP.

Written by the indexing model from the issue text.