anchor.diff:      ((lambda-p exp) (eval-lambda exp env))
       ((if-p exp) (eval-if exp env))
       ((cond-p exp) (t-eval (cond->if exp) env))
  +    ((and-p exp) (eval-and exp env))
  +    ((or-p exp) (eval-or exp env))
       ((begin-p exp) (eval-sequence (begin-actions exp) env))
       ((application-p exp) (eval-application exp env))
       (t 'not-implemented)))
  
positive.code: ;;     (if pred2 (begin exp2 ...)
  ;;         (begin exp3 ...)))
  
  
  (defun begin-p (exp)
    (tagged-list-p exp 'begin))
  
  (defun begin-actions (exp)
    (cdr exp))
  
  (defun last-exp-p (exps)
    (null (cdr exps)))
  
negative.code:     (loop
        (fresh-line)
        (format t "LISP> ")
  ;;      (t-print (t-eval (read) env))
        (handler-case
        	  (t-print (t-eval (read) env))
        	(error (e) (princ e))))))
        )))
  