When specifying a Timeline.time value in a timeline, the value is taken
into account after first initializing to the first value in a keyFrame.

The following code
====================================
import javafx.animation.Timeline;
import javafx.lang.Duration.*;
import javafx.animation.KeyFrame;

var Number:Integer = 21;
var dur:Duration = 21s;

var timeline = Timeline{
    repeatCount: 5
    autoReverse: true
    time: dur
    keyFrames: [
    at (0s) {Number => 0 },
    at (26s) {Number => 26} ],
}
timeline.play();

var currentPlayHead = bind Number on replace {
println("Number change:");
println(Number);
}
==========================================
would print:
Number change:
0
Number change:
21
Number change:
22
Number change:
23
....

when expected to start directly with Number value 21.