Single selection logic for a cell, using RxSwift

SingleSelectionCell+RxSwift.swift

class ParentViewModelClass {  

  func singleSelectionCell(_ title: String) -> FormCellBuildable {
        return FormCheckmarkCellModel(
            title: title, selected: false,
            didSelect: { model in
                // create single use subscription
                let _ = self.selectedValue.asObservable().withPrevious(startWith: nil).take(1)
                    .filter { $0.1 != nil }.map { ($0.0, $0.1!) }
                    .subscribe(onNext: { from, to in
                        from?.selected.value = false
                        to.selected.value = true })

                // signal change to selected, triggering the above
                self.selectedValue.value = model }).cell
  }
  
  lazy var selectedValue = Variable<FormCheckmarkCellModel?>(nil)
}