The poet and playwright on whiteness, power, and class. "There’s a deep psychological need for whiteness to go unexamined. White people have one understanding about what whiteness is and to trouble it is to trouble them. And they cannot hold it, they really cannot bear it, but it really doesn’t have anything to do with me." Claudia Rankine opens up to the Guardian's Afua Hirsch about her experience of being a first-generation immigrant living in the US today.