String namedIndex = Text.getText(Interpreter.send(context.runtime.asText, context, arg));
Integer ix = Regexp.getRegexp(getRegexp(on)).groupId(namedIndex);
if(ix == null || !mr.isCaptured(ix)) {
return context.runtime.nil;
}
return context.runtime.newText(mr.group(ix));
} else {
int size = mr.groupCount();
if(IokeObject.data(arg) instanceof Range) {
int first = Number.extractInt(Range.getFrom(arg), message, context);