code: def _get_user_agent(self, **kwargs) -> str:
      return build_hf_headers(**kwargs)["user-agent"]
  
imports: import unittest
  from unittest.mock import Mock, patch
  from huggingface_hub.utils import get_hf_hub_version, get_python_version
  from huggingface_hub.utils._headers import _deduplicate_user_agent, _http_user_agent, build_hf_headers
  from .testing_utils import handle_injection_in_test
label_desc: Use image node_id 1 for calling the TestUserAgentHeadersUtil obj's underlying member method code with example usage: obj._get_user_agent() and returns: build_hf_headers