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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 open_stream(self, class_attr_name=None, fn=None):
 """ Save an arff structure to a file, leaving the file object open for writing of new data samples. This prevents you from directly accessing the data via Python, but when generating a huge file, this prevents all your data from being stored in memory. """

        if fn:
            self.fout_fn = fn
        else:
            fd, self.fout_fn = tempfile.mkstemp()
            os.close(fd)
        self.fout = open(self.fout_fn, 'w')
        if class_attr_name:
            self.class_attr_name = class_attr_name
        self.write(fout=self.fout, schema_only=True)
        self.write(fout=self.fout, data_only=True)
        self.fout.flush()