Question: What song from Rihanna's album "Unapologetic" did pianist Tokio Myers play in semi-final 3 of the 2017 reality show "Britain's Got Talent"?
Sentence (from "Diamonds (Rihanna song)"): The song's lyrics serve as a departure from the themes of unhealthy relationships that were on Rihanna's previous singles and contain a prominent concept of love.
Relevant evidence: No