Assuming you meant 'busy_bever' to implement the busy beaver function, said function is in fact not a computable function, which means you can't write it down in a programming language.
This is true but somewhat misleading. The nth busy beaver numbers are known for n <= 4. It's within the bounds of possibility that we will some day learn the nth busy beaver numbers for n <= 10. (What we can say is that the parent's loop will never terminate for any known definition of "ever" that pertains to the physical universe.)