code: async def get_initial_offset_async(self): # throws InterruptedException, ExecutionException
          
          _logger.info("Calling user-provided initial offset provider %r %r",
                       self.host.guid, self.partition_id)
          starting_checkpoint = await self.host.storage_manager.get_checkpoint_async(self.partition_id)
          if not starting_checkpoint:
              # No checkpoint was ever stored. Use the initialOffsetProvider instead
              # defaults to "-1"
              self.offset = self.host.eph_options.initial_offset_provider
              self.sequence_number = -1
          else:
              self.offset = starting_checkpoint.offset
              self.sequence_number = starting_checkpoint.sequence_number
  
          _logger.info("%r %r Initial offset/sequenceNumber provided %r/%r",
                       self.host.guid, self.partition_id, self.offset, self.sequence_number)
          return self.offset
docs: Gets the initial offset for processing the partition.
  
          :rtype: str