What is "iamsu!"

Sudan Ameer Williams (born November 16, 1989) better known by his stage name Iamsu!, is an American rapper, singer, songwriter, and record producer most known for his feature on "Up!" and his single "Famous". He has produced and featured many artists such as Tinashe, Sage the Gemini, Kehlani, Hit Boy, Wiz Khalifa, 2 Chainz, DJ Mustard, Casey Veggies, Lil B, G-Eazy, and the HBK Gang.