S9 LIB  (pretty-print object)     ==>  unspecific
        (pretty-print #t object)  ==>  unspecific
        (pretty-print #f object)  ==>  unspecific
        (pp object)               ==>  unspecific
        (pp #t object)            ==>  unspecific
        (pp #f object)            ==>  unspecific
        (pp-file string)          ==>  unspecific

Pretty-print Scheme forms or files. When the first argument of PP
is #T, format OBJECT as code. When the first argument is #F, format
OBJECT as data. When there is only one argument, pass it to PROGRAM?
to figure out wehther it is code or data.

PRETTY-PRINT is just a more verbose name for PP.

PP-FILE pretty-prints all objects in the file STRING.

NOTE: This program handles only a subset of R4RS Scheme correctly
and removes all comments from its input program. Caveat utilitor.

(pp '(let ((a 1) (b 2)) (cons a b)))  ==>  unspecific

Output:  (let ((a 1)
               (b 2))
           (cons a b))
