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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 save(self, filename=None):
 """ Save the smart object to a file. :param filename: File name to export. If None, use the embedded name. """

        if filename is None:
            filename = self.filename
        with open(filename, 'wb') as f:
            f.write(self.data)