//this relies on the Ruby rounding enumerations == Java ones, which they (currently) all are
private static RoundingMode javaRoundingModeFromRubyRoundingMode(Ruby runtime, IRubyObject arg) {
if (arg instanceof RubySymbol) {
RubySymbol roundingModeSymbol = (RubySymbol) arg;
String roundingModeString = roundingModeSymbol.asJavaString();
if (roundingModeString.equals("up")) {
return RoundingMode.UP;
} else if (roundingModeString.equals("down") || roundingModeString.equals("truncate")) {
return RoundingMode.DOWN;
} else if (roundingModeString.equals("half_up") || roundingModeString.equals("default")) {