anchor.diff:  
   (defmacro with-msg-init-data ((var data &key (encoding *default-foreign-encoding*))
                                 &body body)
  -  "Evaluate BODY in an environment where VAR is binded to a new message filled
  +  "Evaluate BODY in an environment where VAR is bound to a new message filled
   with DATA. If DATA is a string, it is encoded using the character coding
   schema ENCODING."
     `(with-foreign-object (,var 'msg)
  
positive.code:   (call-ffi -1 '%term context))
  
  (defmacro with-context ((var io-threads) &body body)
    "Evaluate BODY in an environment where VAR is binded to a context created
  with IO-THREADS threads."
    `(let ((,var (init ,io-threads)))
       (unwind-protect
  
negative.code:   (call-ffi -1 '%close socket))
  
  (defmacro with-socket ((var context type) &body body)
    "Evaluate BODY in an environment where VAR is bound to a socket created in
  context CONTEXT with type TYPE."
    `(let ((,var (socket ,context ,type)))
       (unwind-protect
  