code: def get_user(boto3_session: boto3.session.Session) -> str:
      sts = boto3_session.client("sts")
      response = sts.get_caller_identity()
      arn = response["Arn"]
      assert isinstance(
          arn, str
      ), f"expected a string Arn but got {arn}"
      return arn.split("/")[-1]
  
imports: import sys
  import threading
  import time
  from typing import Any, Callable, Dict, List, Optional, Tuple
  import boto3
  import tqdm
  from botocore.exceptions import ClientError, WaiterError
  from determined.deploy.aws import constants
label_desc: Use image node_id 2 for calling a global function with example usage: get_user(boto3_session) and returns: arn