code: public static UnsignedInteger valueOf(long value) {
      checkArgument(
          (value & INT_MASK) == value,
          "value (%s) is outside the range for an unsigned integer value",
          value);
      return fromIntBits((int) value);
    }
docs: Returns an {@code UnsignedInteger} that is equal to {@code value}, if possible. The inverse
  operation of {@link #longValue()}.