code: def test_string(self):
      df = self.nybb.copy()
      df["string"] = pd.array([1, 2, 3, 4, 5], dtype="string")
      m = df.explore("string")
      out_str = self._fetch_map_string(m)
      assert '"__folium_color":"#9edae5","string":"5"' in out_str
  
imports: import geopandas
  import numpy
  import pandas
  import pytest
  import shapely
  from packaging.version import Version
  from matplotlib import cm
  from matplotlib import colors
  from branca.colormap import StepColormap
label_desc: Use image node_id 12 for calling the TestExplore obj's underlying member method code with example usage: obj.test_string() without return types