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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 ensure_newline(self, n):
 """Make sure there are 'n' line breaks at the end."""

        assert n >= 0
        text = self._output.getvalue().rstrip('\n')
        if not text:
            return
        self._output = StringIO()
        self._output.write(text)
        self._output.write('\n' * n)
        text = self._output.getvalue()
        assert text[-n-1] != '\n'
        assert text[-n:] == '\n' * n