rela_stack_pop
err = rela_stack_pop(&opr1, rela_stack, rela_stack_top);
err = rela_stack_pop(&opr3, rela_stack, rela_stack_top);
err = rela_stack_pop(&opr2, rela_stack, rela_stack_top);
err = rela_stack_pop(&opr1, rela_stack, rela_stack_top);
err = rela_stack_pop(&opr1, rela_stack, rela_stack_top);