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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 _if_not_freed(f):
 """Run the method iff. the memory view hasn't been closed."""

    @add_signature_to_docstring(f)
    @functools.wraps(f)
    def f_(self, *args, **kwargs):
        if self._freed:
            raise OSError
        return f(self, *args, **kwargs)

    return f_