docs: private void convertProductions() throws TreeException, GrammarException {
  	productions = new ProductionSet();
  	ParseTreeNode productionsTree = parserTree.getChild("Productions");
  	ParseTreeNode productionDefinitions = productionsTree
  		.getChild("ProductionDefinitions");
  	for (ParseTreeNode productionDefinition : productionDefinitions
  		.getChildren("ProductionDefinition")) {
  	    convertProductionGroup(productionDefinition);
  	}
      }