anchor.diff:                 (^= . 14)
                  (\|= . 14)
   
  +               (|,| . 14)
  +
                  ))))
     (defun op-precedence (op)
       (if-let ((p (gethash op hash)))
  
positive.code: (defun precedence (e)
    (etypecase e
      (cgen-op (op-precedence (cgen-op-op e)))
      (number 99)
      (rope 99)))
  
  (defun cgen-op-symbol (op)
    "Return the canonical symbol of op"
  
negative.code:               ((:band) '&)
                ((:= =) '=)
                (otherwise op))))
      (assert (op-precedence op))
      op))
  
  
  