premise: Kesha sings, writes songs, and raps for a living.
hypothesis: Kesha Rose Sebert ( [ ˈkɛʃə_roʊz_ˈsɛbərt ] ; born March 1 , 1987 ; formerly stylized as Ke $ ha ) is an American singer , songwriter , and rapper . At the same time , she continued to write songs for other artists , including `` Till the World Ends '' for Britney Spears .