public function addProvider($provider)
    {
        if (!in_array($provider, $this->getServiceProviders())) {
            $quote = $this->getQuoteType('providers');
            $separator = $this->getArrayItemsSeparator('providers');
            $anchor = $this->getInsertPoint('providers');

            $insert = $separator . $quote . $provider . $quote . ',';

            $this->write($insert, $anchor);
        }
    }