//to represent a nonempty list of phone entries
public class ConsPhList implements IPhList { 
  private PhEntry first; 
  private IPhList rest; 

  public ConsPhList(PhEntry first, IPhList rest){ 
    this.first = first; 
    this.rest = rest; 
  } 

  // represent this list as a string
  public String toString(){ 
    return 
    new String("new ConsPhList(" + "first: "+ this.first.toString() + 
        ",\n" + "rest: "+ this.rest.toString() + ")"); 
  }
}