Please try it and attempt to produce a case of breakage.

In my tests it works perfectly.

In theory it should work fine as well.

If A is an abstract class and B inherits from it then the check that B has implemented the methods does not happen when B calls import on A since A ignores the method call with itself as the class. It only happens when A handles the call to import B into whatever C wanted to use it, at which point B has been compiled and loaded.