public Annotations getAnnotation(int from, int to, AnnotationClass clazz) {
        if (from < this.from || to > this.to) {
            throw new RuntimeException("Trying to get a range that is outside this span");
        }
        if (this.parent != null) {
            return parent.getAnnotation(from, to, clazz);
        } else {
            return getBestAnnotation(from, to, clazz );

        }
    }
Returns the annotations with a specific class for the area defined by (from,to).

This function will query its parent to find any annotation that is set for an area that this span is contained
in. If there are conflicts (several annotations defined with the same annotation class), the annotation
that is defined for the smallest area (furthest down in the tree), is used.

@throws RuntimeException if (from,to) is not contained in the span
container-search/src/main/java/com/yahoo/text/interpretation/Span.java