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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 _feed_line(self, line):
 """Put the given line into the callback machinery, and set the result on a None line."""

        if line is None:
            self.set_result(self._callback(self.__spooled_lines))
        else:
            self.__spooled_lines.append(line)