anchor.diff:  
   (defun blank-line-p ()
     (let ((string (current-line-string))
  -        (eof-p (tail-line-p)))
  +        (eof-p (end-line-p)))
       (when (string= "" (string-trim '(#\space #\tab) string))
         (+ (length string)
            (if eof-p 0 1)))))
  
positive.code: (in-package :lem)
  
  (export '(start-line-p
            tail-line-p
            bolp
            eolp
            bobp
  
negative.code: (defun start-line-p ()
    (<= (current-linum) 1))
  
  (defun end-line-p ()
    (<= (buffer-nlines (current-buffer))
        (current-linum)))
  
  