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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 to_csv(self, file: str, opts: dict = None) -> str: """ This method will export a SAS Data Set to a file in CSV format. :param file: the OS filesystem path of the file to be created (exported from this SAS Data Set) :return: """

        opts = opts if opts is not None else {}
        ll = self._is_valid()
        if ll:
            if not self.sas.batch:
                print(ll['LOG'])
            else:
                return ll
        else:
            return self.sas.write_csv(file, self.table, self.libref, self.dsopts, opts)