code: package edu.berkeley.nlp.syntax;
  
  import java.io.BufferedReader;
  import java.io.FileInputStream;
  import java.io.FileNotFoundException;
  import java.io.InputStreamReader;
  
  import edu.berkeley.nlp.util.Iterators;
  import edu.berkeley.nlp.util.StrUtils;
  
  public class TreeStripper {
  
  	public static void main(String argv[]) throws FileNotFoundException {
  		BufferedReader inputData = (argv.length == 0) ? new BufferedReader(
  				new InputStreamReader(System.in)) : new BufferedReader(
  				new InputStreamReader(new FileInputStream(argv[0])));
  		for (Tree<String> tree : Iterators.able(new Trees.PennTreeReader(
  				inputData))) {
  			tree = new Trees.EmptyNodeStripper().transformTree(tree);
  			System.out.println(StrUtils.join(tree.getYield()));
  		}
  	}
  
  }
  