Function ones_array 

const fn ones_array<const B: usize, const N: usize, U>() -> Array<Elem<BaseField>, U>
where
    U: ArraySize<ArrayType<Elem<BaseField>> = [Elem<BaseField>; N]>,
    Const<N>: ToUInt<Output = U>,

To speed up CBD sampling, we pre-compute all the bit-manipulations:

• Splitting a sampled integer into two parts
• Counting the ones in each part
• Taking the difference between the two counts mod q