I would like to introduce partial type annotation to my project. For example for overloading. I found that pep561 introduce partial stub file support. I develop my project with PyCharm and I add ...

I'm new to Python annotation (type hints). I noticed that many of the class definitions in pyi files inherit to Generic[_T], and _T = TypeVar('_T'). I am confused, what does the _T mean here？ from ...