anchor.diff:    
   (defmacro define-get-sockopt (os eql-name helper-get level optname)
     `(defmethod get-socket-option ((socket socket) (option-name (eql ,eql-name)))
  -     ,(if (member os *features*)
  +     ,(if (featurep os)
             `(with-socket-error-filter
                (,helper-get (socket-fd socket) ,level ,optname))
             `(error 'option-not-available option-name))))
   
   (defmacro define-set-sockopt (os eql-name args helper-set level optname)
     `(defmethod set-socket-option ((socket socket) (option-name (eql ,eql-name)) &key ,@args)
  -     ,@(if (member os *features*)
  +     ,@(if (featurep os)
              `((with-socket-error-filter
                  (,helper-set (socket-fd socket) ,level ,optname ,@args)))
              `((declare (ignore ,@args))
  
positive.code: 
  (eval-when (:compile-toplevel :load-toplevel :execute)
    (defun make-sockopt-helper-name (action value-type)
      (concat-symbol action
                                 '-socket-option-
                                 value-type))
  
    (defvar +helper-args-map+
      '((:bool (value))
  
negative.code: 
  ;; TODO: implement "struct ucred" helpers
  
  ;; (define-socket-option pass-credentials   :get-and-set et:so-passcred     et:sol-socket :ucred   (or :linux :freebsd))
  ;; (define-socket-option peer-credentials   :get         et:so-peercred     et:sol-socket :ucred   (or :linux :freebsd))
  
  
  ;; TODO: implement "struct accept_filter_arg" helpers
  