Really nice open source library on github

You need to get good. There's not always going to be documentation. Just look at the source code and try to understand the architecture based on the method signatures and implementations.

Why don't you read the code and write down the functions you want to use in a text file?

Just weigh out if it's faster to figure out their implementation vs writing your own. I do this probably every fucking day. "Do I really need to use a library or will it be just as fast to write a dozen lines myself?" Consider if the task is complex, and if the available libraries have bugs and/or are testable.

>develop software at work
>code made by other colleagues never have documentation or even comments
>they get mad when I do it with my own code
Why do they do this?

Sounds like the perfect first pull request.

if its truly small size you don't need documentation or community or tutorials

If you write documentation for your code.
You are a bad coder. Period. &
Remember, only brainlets need documentation

nobody ever reads documentation even if its there, so why write it

How the fuck can you know it's perfect if you don't know how to use it.
You're the problem OP.

If you have to document you're writing spaghetti

If your project is well documented you and your colleagues are easier to replace.