When a statutory provision is unclear about its purpose, what is the test for determining its purpose?

When a statutory provision is unclear, we will "[d]ecide what purpose ought to be attributed to the statute and to any subordinate provision of it which may be involved[,] and then [ ] [i]nterpret the words of the statute immediately in question so as to carry out the purpose as best it can." United States v. Miguel, 49 F.3d 505, 509 (9th Cir.1995) (quotation omitted). In the present case, we think " 'the answer is to be found by examining the purpose of the statute and the entirety of its text.' " Id. at 509 (brackets omitted) (quoting United States v. Fausto, 484 U.S. 439, 444, 108 S.Ct. 668, 672, 98 L.Ed.2d 830 (1988)).