          .onDelete { viewStore.send(.remove($0)) }
        }
      }
      .navigationBarTitle(viewStore.state.isEmpty ? "Untitled" : viewStore.state)
      .navigationBarItems(
        trailing: Button("Add row") { viewStore.send(.append) }
      )
    }
  }
}

extension NestedState {
  static let mock = NestedState(
    children: [