premise: Macklemore sings with Ryan Lewis.
hypothesis: Macklemore . He has significantly collaborated with producer Ryan Lewis as Macklemore & Ryan Lewis . Macklemore and Ryan Lewis 's single `` Thrift Shop '' reached number one on the U.S. Billboard Hot 100 in 2013 . Their second single , `` Ca n't Hold Us '' , also peaked at number one of the Hot 100 Chart , making Macklemore and Lewis the first duo in the chart 's history to have their first two singles both reach the peak position .