void fuga(coroutine *frame)
{
    // arguments can be accessed via frame->env
    int piyo = *((int *)(frame->env)) + 10;
    // call yield to yield a value.
    yield(frame, &piyo);
    // if NULL is yielded, the coroutine ends
    // yield(frame, NULL);
    // or just returning ends the coroutine as well.
}

coroutine *hoge = new_coroutine(function_to_call, (void *)&arguments);

while ((ret = call_coroutine(context)) != NULL)
{
    printf("%d\n", *ret);
}