What is the test for determining whether a defendant has the ability to pay a restitution fine?

restitution fine. Whatever is necessarily implied in a statute is as much a part of it as that which is expressed. [Citations.] The statute thus impliedly presumes a defendant has the ability to pay and expressly places the burden on a defendant to prove lack of ability. Where, as here, a defendant adduces no evidence of inability to pay, the trial court should presume ability to pay, as the trial court correctly did here. Since here defendant's ability to pay was supplied by the implied presumption, the record need not contain evidence of defendant's ability to pay." (People v. Romero (1996) 43 Cal.App.4th 440, 448-449.)