anchor.diff:             (assert (stream-accepts-characters? stream))
              (extend-vector-output-stream-buffer sequence stream :start start :end end))))
       ((vector (unsigned-byte 8))
  +     ;; specialized branch to help inlining
  +     (check-if-accepts-octets stream)
  +     (extend-vector-output-stream-buffer sequence stream :start start :end end))
  +    (vector
        (check-if-accepts-octets stream)
        (extend-vector-output-stream-buffer sequence stream :start start :end end)))
     sequence)
  
positive.code:   (incf (vector-stream-index stream))
    byte)
  
  (defmethod stream-write-char ((stream vector-output-stream) char)
    (declare (optimize speed))
    (check-if-open stream)
  
negative.code: 
  (declaim (inline check-if-open check-if-accepts-octets
            check-if-accepts-characters stream-accepts-characters?
            stream-accepts-octets? vector-extend extend-vector-output-stream-buffer))
  
  ;;; Some utilities (on top due to inlining)
  
  (defun vector-extend (extension vector &key (start 0) (end (length extension)))
    ;; copied over from cl-quasi-quote
    (declare (optimize speed)
             (type vector extension vector)
             (type array-index start end))
    (let* ((original-length (length vector))
           (extension-length (- end start))
           (new-length (+ original-length extension-length))
           (original-dimension (array-dimension vector 0)))
      (when (< original-dimension new-length)
        (setf vector (adjust-array vector (max (* 2 original-dimension) new-length))))
      (setf (fill-pointer vector) new-length)
      (replace vector extension :start1 original-length :start2 start :end2 end)
      vector))
  
  (defclass in-memory-stream (trivial-gray-stream-mixin)
    ((element-type :initform :default ; which means bivalent
  