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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 raise_io_error(self, errno, filename=None):
 """Raises IOError. The error message is constructed from the given error code and shall start with the error in the real system. Args: errno: A numeric error code from the C variable errno. filename: The name of the affected file, if any. """

        raise IOError(errno, self._error_message(errno), filename)