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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 set_datetime_format(self, format):
 """ Set the Accept-Datetime-Format header to an acceptable value Args: format: UNIX or RFC3339 """

        if not format in ["UNIX", "RFC3339"]:
            return

        self.datetime_format = format

        self.set_header("Accept-Datetime-Format", self.datetime_format)