code: def test__repr_html_is_str(m):
      html = m._repr_html_()
      assert isinstance(html, str)
  
file_path: folium/tests/test_repr.py
imports: import io
  import PIL.Image
  import pytest
  import folium
label_desc: Use image node_id 3 for calling a global function with example usage: test__repr_html_is_str(m) without return types