code: public static <T> String listToString(List<T> list, final boolean justValue) {
      return listToString(list, justValue, null);
    }
docs: Returns the sentence as a string with a space between words.
  Designed to work robustly, even if the elements stored in the
  'Sentence' are not of type Label.
  
  This one uses the default separators for any word type that uses
  separators, such as TaggedWord.
  
  @param justValue If <code>true</code> and the elements are of type
  <code>Label</code>, return just the
  <code>value()</code> of the <code>Label</code> of each word;
  otherwise,
  call the <code>toString()</code> method on each item.
  @return The sentence in String form