(use-modules (ice-9 gap-buffer))

(define buffer (make-gap-buffer ""))

(define data
  "aaaaa\nbbbbb\nccccc\nddddd\neeeee\nffff\nggggg\nhhhhh\niiiii\njjjjj\nkkkkk\nlllll\n")

(gb-insert-string! buffer data)

(display "Before goto-char: ")
(newline)
(display (gb->string buffer))
(newline)

(gb-goto-char buffer (gb-point-min buffer))

(display "After goto-char:")
(newline)
(display (gb->string buffer))
(newline)