S9 LIB  (write-to-string object)    ==>  string
        (display-to-string object)  ==>  string

Write the external representation of the given OBJECT to a fresh
string. WRITE-TO-STRING is like WRITE but writes its output to a
string instead of an output port. DISPLAY-TO-STRING is like
DISPLAY but writes its output to a string.

(write-to-string '(a 1 #\c #(v) #t "str" "\"s\"" (a . d)))
  ==>  "(a 1 #\\c #(v) #t \"str\" \"\\\"s\\\"\" (a . d))"

(display-to-string '(a 1 #\c #(v) #t "str" "\"s\"" (a . d)))
  ==>  "(a 1 c #(v) #t str \"s\" (a . d))"
