How to prevent user to login with the same account at the same time

Question

I want prevent user to login with the same account from different devises at the same time , so if the user want to login from different device he must log out from the old device first. iam Flutter and using Google Phone auth by firebase.. I tried similar to this code but didn't work for me

firebase.auth().onAuthStateChanged(firebaseUser => {

   if(firebaseUser){
      // update Newsitems
      firebase.database().ref('news').once('value', function(snap){
         snap.forEach(snapChild => {
             addNewsItemToHTML(snapChild.val(), snapChild.key)
         })
      })
   }
   if(!firebaseUser){
      document.getElementById('newsitems').innerHTML = '';
      document.getElementById('admin').innerHTML = '';
   }
});