Two Way Rx Binding with an infix operator <->

Rx+TwoWayBinding.swift

import Cocoa
import RxSwift
import RxCocoa

infix operator <->

func <-> <T>(property: ControlProperty<T>, variable: BehaviorRelay<T>) -> Disposable {
    let bindToUIDisposable = variable.asObservable()
        .bind(to: property)
    let bindToVariable = property
        .subscribe(onNext: { n in
            variable.accept(n)
        }, onCompleted:  {
            bindToUIDisposable.dispose()
        })
    
    return CompositeDisposable(bindToUIDisposable, bindToVariable)
}
func <-> <T>(property: ControlProperty<T?>, variable: BehaviorRelay<T>) -> Disposable {
    let bindToUIDisposable = variable.asObservable()
        .bind(to: property)
    let bindToVariable = property
        .subscribe(onNext: { n in
            if let n = n {
                variable.accept(n)
            }
        }, onCompleted:  {
            bindToUIDisposable.dispose()
        })
    
    return CompositeDisposable(bindToUIDisposable, bindToVariable)
}
func <-> <T>(property: ControlProperty<T?>, variable: BehaviorRelay<T?>) -> Disposable {
    let bindToUIDisposable = variable.asObservable()
        .bind(to: property)
    let bindToVariable = property
        .subscribe(onNext: { n in
            variable.accept(n)
        }, onCompleted:  {
            bindToUIDisposable.dispose()
        })
    
    return CompositeDisposable(bindToUIDisposable, bindToVariable)
}

func <-> <T>(variable: BehaviorRelay<T>, property: ControlProperty<T?>) -> Disposable {
    let bindToUIDisposable = variable.asObservable()
        .bind(to: property)
    let bindToVariable = property
        .subscribe(onNext: { n in
            if let n = n {
                variable.accept(n)
            }
        }, onCompleted:  {
            bindToUIDisposable.dispose()
        })
    
    return CompositeDisposable(bindToUIDisposable, bindToVariable)
}
func <-> <T>(variable: BehaviorRelay<T?>, property: ControlProperty<T?>) -> Disposable {
    let bindToUIDisposable = variable.asObservable()
        .bind(to: property)
    let bindToVariable = property
        .subscribe(onNext: { n in
            variable.accept(n)
        }, onCompleted:  {
            bindToUIDisposable.dispose()
        })
    
    return CompositeDisposable(bindToUIDisposable, bindToVariable)
}