docs: public AlignedExpressionTree getBestAlignment(AlignmentExample example) {
      CfgParser parser = getCfgParser(example);
      ExpressionTree tree = example.getTree();
      
      Factor rootFactor = getRootFactor(tree, parser.getParentVariable());
      CfgParseChart chart = parser.parseMarginal(example.getWords(), rootFactor, false);
      CfgParseTree parseTree = chart.getBestParseTree();
  
      return decodeCfgParse(parseTree, 0);
    }