     }
 }
 
-func DKKeyframeAnimationFunctionEaseInQuint(var t: Double, b: Double, c: Double, d: Double) -> Double {
-    t /= d
+func DKKeyframeAnimationFunctionEaseInQuint(t: Double, b: Double, c: Double, d: Double) -> Double {
+    let t = t / d
     return c * t * t * t * t * t + b;
 }
 
-func DKKeyframeAnimationFunctionEaseOutQuint(var t: Double, b: Double, c: Double, d: Double) -> Double {
-    t = t / d - 1
+func DKKeyframeAnimationFunctionEaseOutQuint(t: Double, b: Double, c: Double, d: Double) -> Double {
+    let t = t / d - 1
     return c * (t * t * t * t * t + 1) + b;
 }
 
-func DKKeyframeAnimationFunctionEaseInOutQuint(var t: Double, b: Double, c: Double, d: Double) -> Double {
-    t /= d / 2
+func DKKeyframeAnimationFunctionEaseInOutQuint(t: Double, b: Double, c: Double, d: Double) -> Double {
+    var t = t / (d / 2)
     if t < 1 {
         return c / 2 * t * t * t * t * t + b;
     } else {

    }
}

func DKKeyframeAnimationFunctionEaseInQuart(var t: Double, b: Double, c: Double, d: Double) -> Double {
    t /= d
    return c * t * t * t * t + b;
}

func DKKeyframeAnimationFunctionEaseOutQuart(var t: Double, b: Double, c: Double, d: Double) -> Double {
    t = t / d - 1
    return -c * (t * t * t * t - 1) + b;
}

func DKKeyframeAnimationFunctionEaseInOutQuart(var t: Double, b: Double, c: Double, d: Double) -> Double {
    t /= d / 2
    if t < 1 {
        return c / 2 * t * t * t * t + b;
    } else {

    }
}

func DKKeyframeAnimationFunctionEaseInBack(t: Double, b: Double, c: Double, d: Double) -> Double {
    let s = 1.70158
    let t = t / d
    return c * t * t * ((s + 1) * t - s) + b;
}

func DKKeyframeAnimationFunctionEaseOutBack(t: Double, b: Double, c: Double, d: Double) -> Double {
    let s = 1.70158
    let t = t / d - 1
    return c * (t * t * ((s + 1) * t + s) + 1) + b;
}

func DKKeyframeAnimationFunctionEaseInOutBack(t: Double, b: Double, c: Double, d: Double) -> Double {
    var s = 1.70158
    var t = t / (d / 2)

    if t < 1 {
        s *= 1.525
