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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 _step00(self, in_row, tmp_row, out_row):
 """ Prunes whitespace for all fields in the input row. :param dict in_row: The input row. :param dict tmp_row: Not used. :param dict out_row: Not used. """

        for key, value in in_row.items():
            in_row[key] = WhitespaceCleaner.clean(value)

        return None, None