(defun dot () (point))

(defun find-dup-lines-in-file ()
    (interactive)
    (setq dups '())
    (setq fuck '())
    (setq shit '())
    (while (not (eobp))
;       (setq fuck (append fuck (list (what-line))))
	(setq d (dot))
	(end-of-line)
	(setq l1 (buffer-substring d (dot)))
	(next-line 1)
	(beginning-of-line)
	(setq d (dot))
	(end-of-line)
	(setq l2 (buffer-substring d (dot)))
;	(setq shit (append shit (list (concat l1 " " l2))))
	(if (string= l1 l2)
	    (setq dups (append dups (list (concat (what-line) " "))))
	)
	(beginning-of-line)
    )
)