usenum_bigint::BigUint;// Use this when num_limbs is not a constant.
// little endian.
// Warning: This function only returns the last NUM_LIMBS bytes of
// the input, while the input can have more than that.
#[inline(always)]pubfnbiguint_to_limbs_vec(x:&BigUint, num_limbs:usize)->Vec<u8>{
x.to_bytes_le().into_iter().chain(std::iter::repeat(0u8)).take(num_limbs).collect()}