anchor.diff:            (determine-encoding-writer destination 0 canonical-element-type)
           (declare (ignore return-value))
           (make-instance 'encoding-stream
  -                       :wrapped destination
                          :encode-fun encode-fun
                          :encode-table table
                          :writer writer)))))
  
positive.code: (defun make-encoding-stream (destination format &key (element-type 'base-char))
    (multiple-value-bind (encode-fun length-fun table) (encoding-tools format)
      (let ((canonical-element-type (canonicalize-element-type element-type)))
        (when (null destination)
          (case canonical-element-type
            ((character base-char)
  
negative.code: ;;; encoding streams
  
  (defclass encoding-stream (#.*binary-output-stream-class*)
    ((buffer :reader buffer :initarg :buffer)
     (index :accessor index :initform 0)
     (encode-fun :reader encode-fun :initarg :encode-fun)
     (encode-table :reader encode-table :initarg :encode-table)
  