(defun my-copy (source destination)
  (with-open-file (in source :direction :input)
    (with-open-file (out destination :direction :output
			    :if-exists :supersede)
      (do ((line (read-line in nil 'eof)
		 (read-line in nil 'eof)))
	  ((eql line 'eof))
	(format out line)))))