Returns a list of addresses that have been deleted, or None if it
        hasn't been deleted.

        Args:
            addresses (list of str): The addresses to check if deleted.

        Returns:
            (list of str): The addresses, if deleted, or None.

def get_if_deleted(self, addresses):
        """Returns a list of addresses that have been deleted, or None if it
        hasn't been deleted.

        Args:
            addresses (list of str): The addresses to check if deleted.

        Returns:
            (list of str): The addresses, if deleted, or None.
        """

        with self._lock:
            results = []
            for add in addresses:
                results.append(self._get_if_deleted(add))
            return results