Laravel HasManyThrough explanation

hasManyThrough.php

class Current extends Model
{
    public function final()
    {
        return $this->hasManyThrough(
            'App\Final',
            'App\Intermediate',
            'intermediate_id', // Foreign key on Intermediate
            'final_id', // Foreign key on Final
            'id', // Local key on Current
            'id' // Local key on Intermediate
        );
    }
}

Because I'm always forgetting those keys.