diff --git a/src/runtime/animate/index.ts b/src/runtime/animate/index.ts
index c8ad103065..fdbf9ef780 100644
--- a/src/runtime/animate/index.ts
+++ b/src/runtime/animate/index.ts
@@ -1,46 +1,43 @@
 import { cubicOut } from '../easing';
 import { is_function } from '../internal';
-
-// todo: same as Transition, should it be shared?
-export interface AnimationConfig {
-	delay?: number;
-	duration?: number;
-	easing?: (t: number) => number;
-	css?: (t: number, u: number) => string;
-	tick?: (t: number, u: number) => void;
-}
-
-export interface FlipParams {
-	delay?: number;
-	duration?: number | ((len: number) => number);
-	easing?: (t: number) => number;
+/** @param {Element} node
+ * @param {{ from: DOMRect; to: DOMRect }}
+ * @param {FlipParams} params
+ * @returns {import("/Users/elliottjohnson/dev/sveltejs/svelte/index.ts-to-jsdoc").AnimationConfig}
+ */
+export function flip(node, { from, to }, params = {}) {
+    const style = getComputedStyle(node);
+    const transform = style.transform === 'none' ? '' : style.transform;
+    const [ox, oy] = style.transformOrigin.split(' ').map(parseFloat);
+    const dx = from.left + (from.width * ox) / to.width - (to.left + ox);
+    const dy = from.top + (from.height * oy) / to.height - (to.top + oy);
+    const { delay = 0, duration = (d) => Math.sqrt(d) * 120, easing = cubicOut } = params;
+    return {
+        delay,
+        duration: is_function(duration) ? duration(Math.sqrt(dx * dx + dy * dy)) : duration,
+        easing,
+        css: (t, u) => {
+            const x = u * dx;
+            const y = u * dy;
+            const sx = t + (u * from.width) / to.width;
+            const sy = t + (u * from.height) / to.height;
+            return `transform: ${transform} translate(${x}px, ${y}px) scale(${sx}, ${sy});`;
+        }
+    };
 }
 
-export function flip(
-	node: Element,
-	{ from, to }: { from: DOMRect; to: DOMRect },
-	params: FlipParams = {}
-): AnimationConfig {
-	const style = getComputedStyle(node);
-	const transform = style.transform === 'none' ? '' : style.transform;
 
-	const [ox, oy] = style.transformOrigin.split(' ').map(parseFloat);
-	const dx = from.left + (from.width * ox) / to.width - (to.left + ox);
-	const dy = from.top + (from.height * oy) / to.height - (to.top + oy);
 
-	const { delay = 0, duration = (d) => Math.sqrt(d) * 120, easing = cubicOut } = params;
 
-	return {
-		delay,
-		duration: is_function(duration) ? duration(Math.sqrt(dx * dx + dy * dy)) : duration,
-		easing,
-		css: (t, u) => {
-			const x = u * dx;
-			const y = u * dy;
-			const sx = t + (u * from.width) / to.width;
-			const sy = t + (u * from.height) / to.height;
-
-			return `transform: ${transform} translate(${x}px, ${y}px) scale(${sx}, ${sy});`;
-		}
-	};
-}
+/** @typedef {Object} AnimationConfig
+ * @property {number} [delay]
+ * @property {number} [duration]
+ * @property {(t:number)=>number} [easing]
+ * @property {(t:number,u:number)=>string} [css]
+ * @property {(t:number,u:number)=>void} [tick] 
+ */
+/** @typedef {Object} FlipParams
+ * @property {number} [delay]
+ * @property {number|((len:number)=>number)} [duration]
+ * @property {(t:number)=>number} [easing] 
+ */
\ No newline at end of file