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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 fetch_column(self, sql, *args, **kwargs):
 """Executes an SQL SELECT query and returns the first column of the first row or `None`. :param sql: statement to execute :param args: parameters iterable :param kwargs: parameters iterable :return: the first row of the first column or `None` """

        with self.locked() as conn:
            return conn.query(sql, *args, **kwargs).fetch_column()