C++: what's the usage of declaring a function inside another function?

Stanley Lippman's "C++ primer" mentioned, in page 234 that

Ordinarily, it is a bad idea to declare a function locally. However, to explain how scope interacts with overloading, we will violate this practice and use local function declarations.

...
void print(const string &);
void print(double); // overloads the print function
void fooBar(int ival)
{ ...
  // bad practice: usually it's a bad idea to declare functions at local scope
  void print(int); // new scope: hides previous instances of print
  print(ival); // ok: print(int) is visible
  print(3.14); // ok: calls print(int); print(double) is hidden
}

Nevertheless, which situation it might make sense to do so, declaring a function inside the body of a function?

I recall similar code in Scheme:

(define (PowerSet set)
   (if (null? set) '(())
      (let ((PowerSetAfterHead (PowerSet (cdr set) ) ))
         (append PowerSetAfterHead
            (PowerSet (cdr set) )
            (map
               (lambda (subset)
                  (cons (car set) subset
                  )
               )
               (PowerSet (cdr set) )                                 
            )
         )
      )
   )
)

Is it normally used to hide from misuse of a "local function" that intends for the outer function's usage only? something like internal class? Or is it useful in some design patterns?