I'm trying to move objects by keystroke in Unity, but how do I stop processing until keystroke?

If it is a game that is supposed to move frame by frame like action, I think it would be good to add a function of movement processing to Update and loop the function at the frame update interval, but I can't stop processing until I enter a key, for example, like RPG character movement.
The sauce looks like this.

01:void Start(){
02: StartCoroutine (CoroutineSample());
03:}
04:
05:void Update() {
06:}
07: IEnumerator CoroutineSample(){
08: Waitwhile(!Input.anyKeyDown) {yield return 0;} // Stop processing until key is entered
09:
10: if (the action of the character moving up when the key of W is pressed)
11—Multiple else if (move left for A, down for S, and right for D when pressing other keys
12:
13:} // Close CoroutineSample() parentheses

However, now that you build it,

WaitWhile(!Input.anyKeyDown) {yield return 0;} requires (;).

The build does not succeed with an error statement.

Where should I change to make the build successful?

I would appreciate it if you could teach me