merge_destroy (sort->merge);
pqueue_destroy (sort->pqueue);
casewriter_destroy (sort->run);
merge_destroy (sort->merge);
pqueue_destroy (sort->pqueue);
casewriter_destroy (sort->run);
subcase_init_var (&sc, var, SC_ASCEND);
reader = sort_execute (input, &sc);
subcase_init_var (&sc, var, SC_ASCEND);
reader = sort_execute (input, &sc);