Answer to Question #4752 in Python for Evelyn

Question

Hi,
What does it mean by "File name: reference to undefined identifier: read-string" wen I run the below code?
(define (path-demo)
(display "File name: ")
(let ((fname (read-string)))
(let ((infile (open-input-file fname)))
(let ((routes (read infile)))
(display "Start: ")
(let ((start (read-string)))
(display "Finish: ")
(let ((finish (read-string)))
(for-each (lambda (x) (display x) (display " "))
(cons "Route:" (shortest-path start finish routes)))))))))

(define (shortest-path start end net)
(bfs end (list (list start)) net))