docs: public Collection<Procedure1<? super ITreeAppendable>> getGuardEvalationCodeFor(SarlBehaviorUnit source) {
  		assert source != null;
  		final String id = source.getName().getIdentifier();
  		final Collection<Procedure1<? super ITreeAppendable>> evaluators;
  		final Pair<SarlBehaviorUnit, Collection<Procedure1<? super ITreeAppendable>>> pair = this.guardEvaluators.get(id);
  		if (pair == null) {
  			evaluators = new ArrayList<>();
  			this.guardEvaluators.put(id, new Pair<>(source, evaluators));
  		} else {
  			evaluators = pair.getValue();
  			assert evaluators != null;
  		}
  		return evaluators;
  	}