if ($_SERVER['REQUEST_METHOD'] == "POST" && !empty($_POST['username']) && !empty($_POST['password'])) {
        $username = $_POST['username'];
        $password = $_POST['password'];
        $checkuser = is_user_available($connection , $username);

        if($checkuser>0){
          add_user($connection, $username, $password);
        }else{
          echo "I'm sorry but the username you specified has already been taken.  Please pick another one.";
        }
    }