premise: "Hang On" is a song by the band Weezer. The song impacted radio on February 15, 2011. It is the seventh track and second single from their eighth studio album, "Hurley". The album version of "Hang On" is co-written by Rick Nowels and features Canadian actor Michael Cera on backing vocals and pseudo-mandolin. The single version features no mandolin, and contains a harder sound.
hypothesis: "Hang On" featured a piano
reason: We do not know if it featured a piano or not. All we know is that it did not feature a mandolin. 