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12.5.2 Formatter Implementations

Two implementations of formatter objects are provided by this module. Most applications may use one of these classes without modification or subclassing.

`NullFormatter` ([writer])
  A formatter which does nothing. If writer is omitted, a `NullWriter` instance is created. No methods of the writer are called by `NullFormatter` instances. Implementations should inherit from this class if implementing a writer interface but don't need to inherit any implementation.

`AbstractFormatter` (writer)
  The standard formatter. This implementation has demonstrated wide applicability to many writers, and may be used directly in most circumstances. It has been used to implement a full-featured world-wide web browser.