db_param_cleared
select_return_states_hook(PARAM_CLEARED, &db_param_cleared);
db_param_cleared(expr, 6, (char *)"$", (char *)"");
select_return_states_hook(PARAM_CLEARED, &db_param_cleared);
db_param_cleared(expr, PTR_INT(arg), (char *)"$", (char *)"0");
db_param_cleared(expr, PTR_INT(arg), (char *)"$", (char *)"");
select_return_states_hook(PARAM_CLEARED, &db_param_cleared);