Python

You dont really need to "learn to use the library" You are not worth by knowing many libraries, but understanding what they do - and once you understand at a deeper level what those libraries do in background - then library is just that - a collection of code which you can pick up rather quickly as you know how it works from the inside. Web applications all do the same thing. Parse request, calculate something, transform something and returns a response Same goes for any other part of programming. Once you know how it works internally, no language (and especially not a library) is going to be a much of the challenge