MyHelloWorld::sayExclamationMark PHP Method

    public function sayExclamationMark()
    {
        echo '!';
    }

<?php

error_reporting(E_ALL);
trait Hello
{
    public function sayHello()
    {
        echo 'Hello ';
    }
}
trait World
{
    public function sayWorld()
    {
        echo 'World';
    }
}
class MyHelloWorld
{
    use Hello, World;
    public function sayExclamationMark()
    {
        echo '!';
    }
}
$o = new MyHelloWorld();
$o->sayHello();
$o->sayWorld();
$o->sayExclamationMark();