anchor.diff:  (defsetf binary-file (filename &rest args) (sequence)
     `(write-binary-file ,filename ,sequence ,@args))
   
  -;;;; Assembly context protocol (symbol table, accumulated output)
  +;;;; Assembly context protocol
   
   (defvar *context* nil "Current assembly context")
   
  
positive.code:                  :reader context-code-vector
                   :initform (make-array 0 :adjustable t :fill-pointer t))
     (address :initarg :address :accessor context-address :initform #x8000)))
  
  (defmethod context-emit ((context code-vector) bytes)
    (when (> (+ (context-address context) (length bytes)) #x10000)
  
negative.code: 
  (defgeneric context-emit-instruction (context vector)
    (:documentation "Emit an instruction into the assembly context. This
    is a hint, for contexts which want to handle instructions
    specially (e.g. cycle counting).")
    (:method (context vector) (context-emit context vector)))
  
  (defgeneric link (context)
    (:documentation "Prepare and return final, assembled output."))
  
  ;;; Basic implementation of assembly context
  
  