private Optional<Float> trueProbability() {
        if (left.samples().isPresent() && right.samples().isPresent())
            return Optional.of((float)left.samples().get() / (left.samples().get() + right.samples().get()));
        return Optional.empty();
    }
A node in a GBDT tree which references a feature value

@author bratseth
searchlib/src/main/java/com/yahoo/searchlib/gbdt/FeatureNode.java