To enable HTTP connectivity behind corporate firewalls, a number of tools and programming languages support HTTP/HTTPS proxies defined through environment variables like

HTTP_PROXY=http://proxy.com HTTPS_PROXY=https://proxy.com NO_PROXY="*.home.com,another.com" 

Note that there seems to be no consensus on the case of these variables and all-lowercase variable names are also very common. My limited research suggest that at least the following languages automatically obtain and use a proxy from the environment:

• Python
• Go
• Ruby
• R

The request module also supports these variables, but I feel they show be respected by core http and https for best compatibilty.