anchor.diff:      (values (not (zerop (mem-ref flag* :int))) request)))
   
   (defun mpi-wait (request)
  +  "Blocks until REQUEST has been completed."
     (declare (type mpi-request request))
     (with-foreign-objects ((status* '(:struct mpi-status))
                            (request* 'mpi-request))
  
positive.code: (defun mpi-recv (array source &key (comm *standard-communicator*)
                                  start end
                                  (tag +mpi-any-tag+))
    (declare (type simple-array array)
             (type int source tag)
             (type mpi-comm comm)
  
negative.code:     request))
  
  (defun mpi-waitall (&rest requests)
    "MPI-WAITALL blocks until all given requests have been completed. It
  returns REQUESTS."
    (let ((n-requests (length requests)))
      (with-foreign-objects ((requests* 'mpi-request n-requests)
                             (statuses* '(:struct mpi-status) n-requests))
  