;;; helper functions, not part of output interface
(define (escape-parentheses s)
(regexp-substitute/global #f "(^|[^\\])([\\(\\)])" s 'pre 1 "\\" 2 'post))
;;; helper functions, not part of output interface
(define (escape-parentheses s)
(regexp-substitute/global #f "(^|[^\\])([\\(\\)])" s 'pre 1 "\\" 2 'post))