async def write(self, changes: Dict[str, StoreItem]):
        """Save storeitems to storage.

        :param changes:
        :return:
        """
        try:
            # check if the database and container exists and if not create
            if not self.__container_exists:
                self.__create_db_and_container()
                # iterate over the changes
            for (key, change) in changes.items():
                # store the e_tag
                e_tag = change.e_tag
                # create the new document
                doc = {'id': self.__sanitize_key(key),
                       'realId': key,
                       'document': self.__create_dict(change)
                       }
                # the e_tag will be * for new docs so do an insert
                if (e_tag == '*' or not e_tag):
                    self.client.UpsertItem(
                        database_or_Container_link=self.__container_link,
                        document=doc,
                        options={'disableAutomaticIdGeneration': True}
                        )
                # if we have an etag, do opt. concurrency replace
                elif(len(e_tag) > 0):
                    access_condition = {'type': 'IfMatch', 'condition': e_tag}
                    self.client.ReplaceItem(
                        document_link=self.__item_link(
                            self.__sanitize_key(key)),
                        new_document=doc,
                        options={'accessCondition': access_condition}
                        )
                # error when there is no e_tag
                else:
                    raise Exception('cosmosdb_storage.write(): etag missing')
        except Exception as e:
            raise e
Save storeitems to storage.

        :param changes:
        :return: