@Contract(pure=true)
  public static byte @NotNull [] prepend(byte element, byte @NotNull [] array) {
    int length = array.length;
    byte[] result = new byte[length + 1];
    result[0] = element;
    System.arraycopy(array, 0, result, 1, length);
    return result;
  }
@Contract(pure=true)
  public static byte @NotNull [] prepend(byte element, byte @NotNull [] array)