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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 _validate_page(self):
 """ Run PageValidator on the PAGE-XML documents referenced in the METS. """

        for ocrd_file in self.mets.find_files(mimetype=MIMETYPE_PAGE, local_only=True):
            self.workspace.download_file(ocrd_file)
            page_report = PageValidator.validate(ocrd_file=ocrd_file, strictness=self.page_strictness)
            self.report.merge_report(page_report)