anchor.diff:  (defun mpi-irecv-anything (source &key (comm *standard-communicator*)
                                       (tag +mpi-any-tag+)
                                       (decode *standard-decode-function*))
  +  "Returns a request that can be passed to MPI-WAITALL-ANYTHING to receive
  +an arbitrary object from a matching MPI-ISEND-ANYTHING."
     (declare (type (signed-byte 32) source tag)
              (type mpi-comm comm))
     (let ((metadata-buffer
  
positive.code:   "MPI-SEND-ANYTHING is a slower but more general variant of MPI-SEND. It can
    transmit any object to a matching MPI-RECV-ANYTHING."
    (mpi-waitall-anything
     (mpi-isend-anything object dest :comm comm :tag tag :encode encode :cleanup cleanup)))
  
  (defun mpi-recv-anything (source &key (comm *standard-communicator*)
                                     (tag +mpi-any-tag+)
                                     (decode *standard-decode-function*))
    (mpi-waitall-anything
     (mpi-irecv-anything source :comm comm :tag tag :decode decode)))
  
  ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
  ;;;
  
negative.code: (defun run-hook (request)
    (funcall (hook request)))
  
  (defun mpi-waitall-anything (&rest requests)
    "REQUESTS must be objects returned by MPI-ISEND-ANYTHING or
    MPI-IRECV-ANYTHING. Block until all given requests have been
    completed. Return a list with one (SOURCE TAG DATA) triple per
    MPI-IRECV-ANYTHING request."
    (let ((data-requests (mapcar #'run-hook (apply #'mpi-waitall requests))))
      (delete-if #'not (mapcar #'run-hook (apply #'mpi-waitall data-requests)))))
  
  (defun mpi-isend-anything (object dest &key (comm *standard-communicator*)
                                           (tag 0)
                                           (encode *standard-encode-function*)
                                           (cleanup *standard-cleanup-function*))
    "MPI-SEND-ANYTHING is a slower but more general variant of MPI-SEND. It
    can transmit any object to a matching MPI-IRECV-ANYTHING when passed to
    MPI-WAITALL-ANYTHING."
    (declare (type (signed-byte 32) dest tag)
             (type mpi-comm comm))
    (let* ((data-buffer
  