anchor.diff:              | None -> NotFound
   
       // updateMembers : MemberList -> Node -> NodeStatus -> MemberList
  -    let private updateMembers memberList memb status =
  +    let private updateMembers memb status memberList =
           let { Members = members } = memberList
           let members' = Map.add memb status members
           // disseminate information
  
positive.code:     | Ping of SeqNumber
      | PingRequest of SeqNumber * Node
      | Ack of SeqNumber * Node
  
  [<RequireQualifiedAccess>]
  module Sequence =
      let make() = SeqNumber(0UL)
      let incr = function
          | SeqNumber s -> SeqNumber(s + 1UL)
  
  [<RequireQualifiedAccess; CompilationRepresentation(CompilationRepresentationFlags.ModuleSuffix)>]
  module IncarnationNumber =
      let make() = IncarnationNumber(0UL)
      let incr = function
          | IncarnationNumber i -> IncarnationNumber(i + 1UL)
  
  module Disseminate =
      type Disseminator = private { T: obj }
  
      // membership : Disseminator -> Node -> NodeStatus -> unit
      let membership disseminator node status = ()
  
      // user : Disseminator -> string -> unit
      let user disseminator event = ()
  
  
  module Membership =
      type MemberList =
          private { Local : Node
                    Incarnation : IncarnationNumber
                    Members : Map<Node, NodeStatus>
                    PeriodTimeout : TimeSpan }
  
      type private FindResult =
          | Local of IncarnationNumber
          | Member of NodeStatus
          | NotFound
  
      // disseminate : MemberList -> Node -> NodeStatus -> unit
      let private disseminate memberList memb status =
          ()
  
      // tryFind : MemberList -> Node -> FindResult
      let private tryFind memberList memb =
          let { Local = local
                Incarnation = currentIncarnation
                Members = members } = memberList
  
negative.code:         { memberList with Members = members' }
  
      // stillAlive : MemberList -> IncarnationNumber -> MemberList
      let private stillAlive incarnation memberList =
          let { Local = local
                Incarnation = currentIncarnation } = memberList
          let incarnation' =  if currentIncarnation > incarnation then currentIncarnation
  