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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 _post_tags(self, fileobj):
 """Raises ogg.error"""


        page = OggPage.find_last(fileobj, self.serial, finishing=True)
        if page is None:
            raise OggVorbisHeaderError
        self.length = page.position / float(self.sample_rate)