Libraries are collections of shared code. They're common in Python, where they're also called "modules," but they're also ...

percall: Average time per call for tottime, derived by taking tottime and dividing it by ncalls. cumtime: Total time spent in the function, including calls to other functions.

Python type hints are used ahead of time, by the type-checking system; for instance, in your editor or IDE. In other words, Python’s type hints are for the developer, not the runtime.