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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def _clear_callbacks(self) -> None: """Clears the callback attributes. This allows the request handler to be garbage collected more quickly in CPython by breaking up reference cycles. """

        self._write_callback = None
        self._write_future = None  # type: Optional[Future[None]]
        self._close_callback = None  # type: Optional[Callable[[], None]]
        if self.stream is not None:
            self.stream.set_close_callback(None)