Icmpv4_packettype subheader = | Id_and_seq of Cstruct.uint16 * Cstruct.uint16| Next_hop_mtu of Cstruct.uint16| Pointer of Cstruct.uint8| Address of Ipaddr.V4.t| Unusedval pp : Format.formatter -> t -> unitmodule Unmarshal : sig ... endmodule Marshal : sig ... end