code: def test_aws_keys_from_env():
      """
      Function to ensure the DataSink can successfully read in AWS
      credentials from the environment variables
      """
  
      # Init variables
      ds = nio.DataSink()
      aws_access_key_id = "ABCDACCESS"
      aws_secret_access_key = "DEFGSECRET"
  
      # Set env vars
      os.environ["AWS_ACCESS_KEY_ID"] = aws_access_key_id
      os.environ["AWS_SECRET_ACCESS_KEY"] = aws_secret_access_key
  
      # Call function to return creds
      access_key_test, secret_key_test = ds._return_aws_keys()
  
      # Assert match
      assert aws_access_key_id == access_key_test
      assert aws_secret_access_key == secret_key_test
  
imports: import os
  import copy
  import simplejson
  import glob
  import os.path
  from subprocess import Popen
  import hashlib
  from collections import namedtuple
  import pytest
  import nipype
  import nipype.interfaces.io
  from nipype.interfaces.base.traits_extension import isdefined
  from nipype.interfaces.base import Undefined, TraitError
  from nipype.utils.filemanip import dist_is_editable
  from subprocess import check_call, CalledProcessError
label_desc: Use image node_id 10 for calling a global function with example usage: test_aws_keys_from_env() without return types