Function to_radix_digits_le_divide_and_conquer 

fn to_radix_digits_le_divide_and_conquer(
    number: BigUint,
    base: u64,
    power: usize,
    big_bases: &[(BigUint, usize)],
    k: usize,
    res: &mut Vec<u8>,
    radix: u64,
)