Do.this { this in
    
    //do stuff
    this.succeeded(someResult)
    
}.then (name: "result step") { this in
    
    //do more stuff
	
    //every this has an index property and an optional name property
    //which can be useful for debugging and error handling
    print("this: \(this.name ?? String(this.index))")
		
    //you can also access the previous result if needed:
    print("previousResult: \(this.previousResult)")
    //or just the previous value:
    print("previousResult: \(this.previousValue)")
	
    //if you're doing anything async, don't forget to call done()	
    DispatchQueue.main.asyncAfter(deadline: .now() + 2) {
     	
        //async stuff
		
        //btw, result value is optional
        this.succeeded()
    }    
    
}.then (after: 2) { this in

    //you can also add a delay directly
    this.succeeded()

}.then { this in
    
    //if an error happened the chain will break (see catch and finally below)
    let error = SomeError.bummer
    this.failed(error)
    
}.then (on: DispatchQueue.global(qos: .background)) { this in
    
    //this will execute in a background queue
    //(+you can combine this with a delay)
    print("on: \(DispatchQueue.currentLabel)")
    //and you can use swift Result objects
    let result: Result<String, Error> = .success("cool!")
    this.done(result)
    
}.then (on: .main) { this in
    
    //this will be execute in the main queue
    //if you dont specify a queue, this will be executed on the current (last used) queue
    print("on: \(DispatchQueue.currentLabel)")
    this.succeeded(someResult)
    
}.catch { this in
    
    //catch an error, this will point to the step that triggered the error	
    print("catched error: \(this.error) from \(this.name ?? String(this.index))")
    
}.finally { this in
    
    //finally - will execute even if an error happened
    print("finally (previousResult: \(this.previousResult))")
    exp.fulfill()
}