Method from_high_endian

src/datasets.rs:62–65

(arr: &[u8])

impl MnistDigits {

    fn from_high_endian(arr: &[u8]) -> u64 {

        arr.iter().fold(0, |acc, val| acc * 256 + (*val as u64))
    }

    fn read_u32<T: Read>(src: &mut T) -> Result<u32, &'static str> {