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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 _cleanup(self):
 """ Frees lots of non-textual information, such as the fonts and images and the objects that were needed to parse the PDF. """

        self.device = None
        self.doc = None
        self.parser = None
        self.resmgr = None
        self.interpreter = None