public void include(RuleBase include) {
        productionRules.add(new IncludeDirective(include));
        includedNames.addAll(include.includedNames);
        includedNames.add(include.getName());
    }
<p>Include another rule base into this. This <b>transfers ownership</b>
of the given rule base - it can not be subsequently used for any purpose
(including accessing).</p>

<p>Each rule base will only be included by the first include directive encountered
for that rule base.</p>
container-search/src/main/java/com/yahoo/prelude/semantics/RuleBase.java