code: public static BigInteger checkGreaterBig(
      final BigInteger x,
      final String x_name,
      final BigInteger in_lower,
      final String lower_name)
    {
      Objects.requireNonNull(x, "Value");
      Objects.requireNonNull(x_name, "Value name");
      Objects.requireNonNull(in_lower, "Lower");
      Objects.requireNonNull(lower_name, "Lower bound name");
  
      if (x.compareTo(in_lower) > 0) {
        return x;
      }
  
      final var message =
        String.format("%s (%s) <= %s (%s)", x_name, x, lower_name, in_lower);
  
      throw new RangeCheckException(message);
    }
docs: <p> Assert that {@code x} (named {@code x_name}) is greater than {@code
  in_lower} (named {@code lower_name}). </p>
  
  @param x          The checked value
  @param in_lower   The lower bound
  @param x_name     The name of the checked value
  @param lower_name The name of the lower bound
  
  @return x