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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 write(self, file_or_filename):
 """ Writes the case data to file. """

        if isinstance(file_or_filename, basestring):
            file = None
            try:
                file = open(file_or_filename, "wb")
            except Exception, detail:
                logger.error("Error opening %s." % detail)
            finally:
                if file is not None:
                    self._write_data(file)
                    file.close()
        else:
            file = file_or_filename
            self._write_data(file)

        return file