aboul3la/sublist3r ? reverse-engineered prompt

Build me a Python tool that finds subdomains for a domain I give it. I want it to check common public sources like search engines and online services, then combine the results and remove duplicates. It should also have an optional brute force mode to find more subdomains, and let me scan the discovered ones on specific ports like 80 and 443.

Please make it work from the command line with simple flags for the domain, brute force, ports, verbose live output, number of threads, choosing which search sources to use, and saving the results to a text file. It should be easy to run on both Python 2 and Python 3, and it would be great if it can also be imported and used from another Python script as a module.

If you need to look up current docs online for any of the source services or Python libraries, go ahead and do that.