boolean deleteDuplicates()
  {
    Type[] arrayType = new Type(types.size()];
    arrayType = types.toArray(arrayTypes);
    // copy list into set for automatic deletion 
    //   of duplicate entries
    Set set = new HashSet(arrayType);  
    // copy set back into the original list as a list from a set
    original = new LinkedList<Type>(Set.asList(set));

    System.out.println("\n  Duplicates if found have been deleted. 'P' to print.\n");
    return true;
  }