code: def _get_block_device_mappings(self, resources_needed):
      return [
          {
              "DeviceName": "/dev/sda1",
              "Ebs": {
                  "DeleteOnTermination": True,
                  "VolumeSize": int(
                      memstr2int(resources_needed["hdd"])
                      / memstr2int("1g")
                  ),
                  "VolumeType": "standard",
              },
          }
      ]
  
imports: import uuid
  import os
  import base64
  import json
  import yaml
  import six
  import filelock
  import hashlib
  import pickle
  from studio import git_util
  from studio.util import logs
  from studio.storage import storage_util
  from studio.util.gpu_util import memstr2int
  from .cloud_worker_util import insert_user_startup_script
label_desc: Use image node_id 3 for calling the EC2WorkerManager obj's underlying member method code with example usage: obj._get_block_device_mappings(resources_needed) and returns: list