Trait that catches custom methods that are not in the class

CustomFunctionality.php

<?php

trait CustomFunctionality
{
	protected $functions = [];

    public function addMethod(string $name, callable $function)
	{
		$this->functions[$name] = $function;
		return $this;
	}
	
    public function __call(string $name, array $params)
    {
        if (isset($this->functions[$name])) {
            return \call_user_func_array($this->functions[$name], $params);
        }
    }
}

class Test
{
    use \CustomFunctionality;
}

$t = new Test();
$t->addMethod('toLower', function ($str) {
	return strtolower($str);
});

echo $t->toLower('ABC'); // abc