code: async def initialize_stores_async(self):
          
          await self.host.storage_manager.create_checkpoint_store_if_not_exists_async()
          partition_ids = await self.get_partition_ids_async()
          retry_tasks = []
          for partition_id in partition_ids:
              retry_tasks.append(
                  self.retry_async(
                      self.host.storage_manager.create_checkpoint_if_not_exists_async,
                      partition_id=partition_id,
                      retry_message="Failure creating checkpoint for partition, retrying",
                      final_failure_message="Out of retries creating checkpoint blob for partition",
                      max_retries=5,
                      host_id=self.host.host_name))
  
          await asyncio.gather(*retry_tasks)
          return len(partition_ids)
docs: Intializes the partition checkpoint and lease store ensures that a checkpoint
          exists for all partitions. Note in this case checkpoint and lease stores are
          the same storage manager construct.
  
          :return: Returns the number of partitions.
          :rtype: int