v. P. 23(b)(3). The "predominance" requirement demands that "proposed classes are sufficiently cohesive to warrant adjudication by representation." Amchem v. Windsor, 521 U.S. 591, 624, 117 S. Ct. 2231, 138 L. Ed. 2d 689 (1997). "[T]he focus of the predominance inquiry is on whether the defendant's con

hat questions common to the class predominate over' other questions." Lienhart v. Dryvit Sys.. Inc.. 255 F.3d 138, 146 n.4 (4th Cir. 2001) (quoting Amchem. 521 U.S. at 609). But as Wal-Mart made clear, the Rule 23(a) commonality requirement and the Rule 23(b)(3) predominance requirement remain separate