Associate the pool with a database.

        :type database: :class:`~google.cloud.spanner_v1.database.Database`
        :param database: database used by the pool:  used to create sessions
                         when needed.

def bind(self, database):
        """Associate the pool with a database.

        :type database: :class:`~google.cloud.spanner_v1.database.Database`
        :param database: database used by the pool:  used to create sessions
                         when needed.
        """
        super(TransactionPingingPool, self).bind(database)
        self.begin_pending_transactions()