code reuse is actually dangerous though. It's possible to use a library, have an expectation on how it will work, and then forget about that assumption, upgrad

code reuse is actually dangerous though. It's possible to use a library, have an expectation on how it will work, and then forget about that assumption, upgrade/fix something in the library, and proceed to break your assumption. It's a pretty common problem. Often the time saved using a library is worth the small risk, but if we're talking about "how to write correct software" you'll want to be weary of code reuse.