anchor.diff:  (defun is-lambda? (expr)
     (and (consp expr)
          (eq (car expr) 'function)
  -       (listp (cdr expr))
  +       (consp (cdr expr))
          (listp (cadr expr))
          (or (consp (caadr expr))
              (eq (caadr expr) 'lambda))))
  
positive.code: ;;;;
  ;;;; LAMBDA-related utilities.
  
  (defun lambda-call-args (expr)
    (cadadar expr))
  
  (defun lambda-call-body (expr)
    (cddadar expr))
  
  (defun lambda-call-vals (expr)
    (cdr expr))
  
negative.code: 
  (defmacro with-lambda-call ((args vals body call) &rest exprs)
    (with-gensym (tmp start)
      `(with (,tmp ,call
  	   	    ,start (past-lambda ,tmp)
         	    ,args (lambda-call-args ,start)
         	    ,vals (lambda-call-vals ,start)
         	    ,body (lambda-call-body ,start))
         ,@exprs)))
  
  (defun function-arguments (fun)
  