xroot anouar Paypal integration with Laravel 5.1

I have been follow all steps mention in this link. xroot/laravel-paypalpayment and after long days finally the example is done successfully but how to change PaymentMethod from credit_card to paypal and how the code will be ? I'm very beginner in this

this is the php code part for credit card payment

// ### Address
        // Base Address object used as shipping or billing
        // address in a payment. [Optional]
        $addr= Paypalpayment::address();
        $addr->setLine1("3909 Witmer Road");
        $addr->setLine2("Niagara Falls");
        $addr->setCity("Niagara Falls");
        $addr->setState("NY");
        $addr->setPostalCode("14305");
        $addr->setCountryCode("US");
        $addr->setPhone("716-298-1822");

        // ### CreditCard
        $card = Paypalpayment::creditCard();
        $card->setType("visa")
            ->setNumber("4758411877817150")
            ->setExpireMonth("05")
            ->setExpireYear("2019")
            ->setCvv2("456")
            ->setFirstName("Joe")
            ->setLastName("Shopper");


        // ### FundingInstrument
        // A resource representing a Payer's funding instrument.
        // Use a Payer ID (A unique identifier of the payer generated
        // and provided by the facilitator. This is required when
        // creating or using a tokenized funding instrument)
        // and the `CreditCardDetails`
        $fi = Paypalpayment::fundingInstrument();
        $fi->setCreditCard($card);

        // ### Payer
        // A resource representing a Payer that funds a payment
        // Use the List of `FundingInstrument` and the Payment Method
        // as 'credit_card'
        $payer = Paypalpayment::payer();
        $payer->setPaymentMethod("credit_card")
            ->setFundingInstruments(array($fi));

thanks in advance

via Chebli Mohamed