const std::unordered_map<std::string, std::string>* get_properties() const;
const char* get_property(const std::string& key) const;
void set_property(const std::string&, const std::string& value);
+ Host* get_host();
void set_data(void* data) { userdata_ = data; }
void* get_data() { return userdata_; }