void instr()
{
    MIN_ARGUMENTS(1);

    // stringify only if not already a string
    if (_stack->get_type(0) != cmd_string)
    {
        stringstream out;
        ((object*)_stack->back())->show(out);
        _stack->pop_back();

        ostring str;
        str.set(out.str().c_str(), out.str().size());
        _stack->push_back(&str, str.size(), cmd_string);
    }
}

void strout()
{
    MIN_ARGUMENTS(1);
    ARG_MUST_BE_OF_TYPE(0, cmd_string);

    string entry(((ostring*)_stack->back())->_value);
    _stack->pop_back();

    program prog;

    // make program from string in stack level 1
    if (program::parse(entry.c_str(), prog) == ret_ok)
    {
        // run it
        prog.run(*_stack, *_global_heap, &_local_heap);
    }
}