anchor.diff:    STREAM: The stream to output to.
     PRINT-NAME: Whether or not to print the name of the field.
     PRETTY-PRINT: When true, print newlines and indentation."
  +  (unless values
  +    nil) ; If values is NIL, then there is nothing to do.
     (let ((type (proto-class field))
           (msg))
       (cond
  
positive.code:                  (when slot
                     (setf (proto-slot-value object slot) val))))))))))
  
  (defun parse-field (type &key (stream *standard-output*))
    "Parse data of type TYPE from STREAM. This function returns
  the object parsed. If the parsing fails, the function will
  return T as a second value."
  
negative.code:                  (undefined-field-type "While parsing ~S from text format,"
                                         msg-desc type field))
                  ((eq (proto-label field) :repeated)
                   ;; If slot is NIL, then this field doesn't exist in the message
                   ;; so we skip it.
                   (when slot
                     (pushnew slot rslots)
                     (push val (proto-slot-value object slot))))
  