code: def _task_ds_id(
      ds_type, ds_root, flow_name, run_id, step_name, task_id, attempt
  ):
      return ".".join(
          [
              ds_type,
              ds_root,
              flow_name,
              run_id,
              step_name,
              task_id,
              str(attempt),
          ]
      )
  
imports: from __future__ import print_function
  from collections import OrderedDict
  import os
  import sys
  import time
  from tempfile import NamedTemporaryFile
  from hashlib import sha1
  from metaflow.datastore import FlowDataStore
  from metaflow.datastore.content_addressed_store import BlobCache
  from metaflow.exception import MetaflowException
  from metaflow.metaflow_config import CLIENT_CACHE_PATH, CLIENT_CACHE_MAX_SIZE, CLIENT_CACHE_MAX_FLOWDATASTORE_COUNT, CLIENT_CACHE_MAX_TASKDATASTORE_COUNT
  from metaflow.plugins import DATASTORES
label_desc: Use image node_id 18 for calling the FileCache obj's underlying member method code with example usage: obj._task_ds_id(ds_type, ds_root, flow_name, run_id, step_name, task_id, attempt) and returns: str