PHP - Interface inheritance - declaration must be compatible

Question

I have the interface:

interface AbstractMapper
{
    public function objectToArray(ActiveRecordBase $object);
}

And classes:

Answer 1

Another way of implementing this would be:

class Executor
{
    public function objectToArray(AbstractMapper $var)
    {
        $this->convert($var);
    }

    private function convert(Product $var)
    {
        ...
    }
}