rem: scheme_check_proc_arity("call-with-continuation-barrier", 1, 0, argc, argv);
add: scheme_check_proc_arity("call-with-continuation-barrier", 0, 0, argc, argv);
context: call_with_continuation_barrier (int argc, Scheme_Object *argv[]){  scheme_check_proc_arity("call-with-continuation-barrier", 1,			  0, argc, argv);  return scheme_apply(argv[0], 1, NULL);}