Check when text is done being printed?

Hey! So I have this very simple code printing the text contained in a .txt file to a UI text field, one character at a time. Obviously, this takes a small amount of time. What I’d like to do is check (probably in Update to test it out) when this file is done being printed to my game’s UI text element. Can anyone give me a hand with this?
Here’s the code so far:
public string textFile;
public Text txtContents;
float textSpeed = .02f;

// Use this for initialization
void Start () {

    StartCoroutine("RunText");
    
	
}

// Update is called once per frame
void Update () {
	
}
IEnumerator RunText()
{
    var stringBuilder = new StringBuilder();
    TextAsset txtAssets = (TextAsset)Resources.Load(textFile);
    foreach (char c in txtAssets.text)
    {
        stringBuilder.Append(c);
        txtContents.text = stringBuilder.ToString();
        yield return new WaitForSeconds(textSpeed);
        
    }
}

}

after the foreach loop, just set a bool to true!

 // Use this for initialization
 void Start () {
     StartCoroutine("RunText");
     
     
 }
 
 // Update is called once per frame
 void Update () {
     
 }
 IEnumerator RunText()
 {
     var stringBuilder = new StringBuilder();
     TextAsset txtAssets = (TextAsset)Resources.Load(textFile);
     foreach (char c in txtAssets.text)
     {
         stringBuilder.Append(c);
         txtContents.text = stringBuilder.ToString();
         yield return new WaitForSeconds(textSpeed);
         
     }
     someBool = true;
 }