Tokenizers break up text into individual Objects. These objects may be
Strings, Words, or other Objects. A Tokenizer extends the Iterator
interface, but provides a lookahead operation peek(). An
implementation of this interface is expected to have a constructor that
takes a single argument, a Reader.
Removes from the underlying collection the last element returned by
the iterator. This is an optional operation for Iterators - a
Tokenizer normally would not support it. This method can be called
only once per call to next.