msc {
  client,historian,recorder;

  recorder=>historian [ label = "e0 = Entry{id: h0, n: 0, event: Tick}" ] ;
  recorder=>recorder [ label = "h1 = hash(h0)" ] ;
  recorder=>recorder [ label = "h2 = hash(h1)" ] ;
  client=>historian [ label = "Transaction(d0)" ] ;
  historian=>recorder [ label = "Transaction(d0)" ] ;
  recorder=>recorder [ label = "h3 = hash(h2 + d0)" ] ;
  recorder=>historian [ label = "e1 = Entry{id: hash(h3), n: 3, event: Transaction(d0)}" ] ;
  recorder=>recorder [ label = "h4 = hash(h3)" ] ;
  recorder=>recorder [ label = "h5 = hash(h4)" ] ;
  recorder=>recorder [ label = "h6 = hash(h5)" ] ;
  recorder=>historian [ label = "e2 = Entry{id: h6, n: 3, event: Tick}" ] ;
  client=>historian [ label = "collect()" ] ;
  historian=>client [ label = "entries = [e0, e1, e2]" ] ;
  client=>client [ label = "entries.verify(h0)" ] ;
}