code: def extract_boto_args_from_env(env_vars):
      
      boto_args = {}
      for i in ['aws_access_key_id', 'aws_secret_access_key',
                'aws_session_token']:
          if env_vars.get(i.upper()):
              boto_args[i] = env_vars[i.upper()]
      return boto_args
docs: Return boto3 client args dict with environment creds.