"You can nest function declarations, but with limited effect. Nested declarations do not limit the visibility of the inner-defined function, which may be called from anywhere in your program. The inner function does not automatically get the outer function's arguments. And, finally, the inner function cannot be called until the outer function has been called."

That's from "Programming PHP" by Rasmus Lerdorf et al.

This sort of messiness, repeated dozens of times in various ways is why I try my best to avoid PHP.