code: async def get_checkpoint_async(self, partition_id):
          
          lease = await self.get_lease_async(partition_id)
          checkpoint = None
          if lease:
              if lease.offset:
                  checkpoint = Checkpoint(partition_id, lease.offset,
                                          lease.sequence_number)
          return checkpoint
docs: Get the checkpoint data associated with the given partition.
          Could return null if no checkpoint has been created for that partition.
  
          :param partition_id: The partition ID.
          :type partition_id: str
          :return: Given partition checkpoint info, or `None` if none has been previously stored.
          :rtype: ~azure.eventprocessorhost.checkpoint.Checkpoint