float8_e4m3fn   round-trip [1.0, 2.0, 240.0, 448.0] -> [1.0, 2.0, 240.0, 448.0]
float8_e4m3fnuz round-trip [1.0, 2.0, 240.0, 448.0] -> [1.0, 2.0, 240.0, nan]