/// the backends appropriate for use with this document.
/// so, e.g., latex is excluded , if we're using non-TeX fonts
std::vector<std::string> backends() const;
/// the backends appropriate for use with this document.
/// so, e.g., latex is excluded , if we're using non-TeX fonts
std::vector<std::string> backends() const;
/// Return true if language could be set to lang,
/// otherwise return false and do not change language
bool setLanguage(std::string const & lang);
/// Return true if language could be set to lang,
/// otherwise return false and do not change language
bool setLanguage(std::string const & lang);