Paypal rest api - what are the possible payment states?

I am trying to simulate a payment using the paypal rest api. After calling execute I get a response object with the state "approved".

Does anyone know where there is a list of the possible states the api may return?

I presume there are a few others but I can not find the documentation that covers this.

paypal.payment.execute(payment_id, details, function (err, payment) {
        if(err){
            throw err;
        }
        if(payment.state === "approved"){
            done(err, payment);
        }else{
            //handle other states
            done(err, payment);
        }

    });;