10.19. Pure Functions¶
A pure function does not produce side effects. It communicates with the
calling program only through parameters (which it does not modify) and a return
value. Here is the
doubleStuff function from the previous section written as a pure function.
To use the pure function version of
double_stuff to modify
you would assign the return value back to
Once again, codelens helps us to see the actual references and objects as they are passed and returned.