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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 export_warnings(self, export_file):
 """Append an export warnings entry to the journal. This instructs Revit to export warnings from the opened model. Currently Revit will stop journal execution if the model does not have any warnings and the export warnings UI button is disabled. Args: export_file (str):
 full path of the ouput html file """

        warn_filepath = op.dirname(export_file)
        warn_filename = op.splitext(op.basename(export_file))[0]
        self._add_entry(templates.EXPORT_WARNINGS
                                 .format(warnings_export_path=warn_filepath,
                                         warnings_export_file=warn_filename))