20 struct DomainName {  struct
21   static ErrorOr<DomainName> Append(const DomainName& first,
22                                     const DomainName& second);
25   static ErrorOr<DomainName> FromLabels(It first, It last) {  in FromLabels()  argument
36     DomainName result;  in FromLabels()
47   static DomainName GetLocalDomain();
52   DomainName();
53   explicit DomainName(std::vector<uint8_t>&& domain_name);
54   DomainName(const DomainName&);
55   DomainName(DomainName&&) noexcept;
56   ~DomainName();
57   DomainName& operator=(const DomainName&);  argument
58   DomainName& operator=(DomainName&&) noexcept;  argument
60   bool operator==(const DomainName& other) const;
61   bool operator!=(const DomainName& other) const;
66   Error Append(const DomainName& after);  argument
83   bool operator()(const DomainName& a, const DomainName& b) const;  argument
86 std::ostream& operator<<(std::ostream& os, const DomainName& domain_name);