ArgParser::addChoicesToCompletions(std::string const& option,
                                   std::string const& extra_prefix)
{
    if (this->option_table->count(option) != 0)
    {
        OptionEntry& oe = (*this->option_table)[option];
        for (std::set<std::string>::iterator iter = oe.choices.begin();
             iter != oe.choices.end(); ++iter)
        {
            completions.insert(extra_prefix + *iter);
        }
    }
}
ArgParser::addChoicesToCompletions(std::string const& option,
                                   std::string const& extra_prefix)
{
    if (this->option_table->count(option) != 0)
    {
        OptionEntry& oe = (*this->option_table)[option];
        for (std::set<std::string>::iterator iter = oe.choices.begin();
             iter != oe.choices.end(); ++iter)
        {
            completions.insert(extra_prefix + *iter);
        }
    }
}