How do you reuse functions across tasks while developing course?

 When creating a course using the Pycharm Educational Edition, how does one reuse the functions developed as a part of one task into another. For instance, in lesson 1/ task1 a function was developed called sum(a,b):return a+b and now in lesson1/task2 it must be reused again. How can we reuse sum() from one task in another using relative imports?