code: def test_custom_markers(self):
      # Markers
      m = self.cities.explore(
          marker_type="marker",
          marker_kwds={"icon": folium.Icon(icon="star")},
      )
      assert ""","icon":"star",""" in self._fetch_map_string(m)
  
      # Circle Markers
      m = self.cities.explore(
          marker_type="circle", marker_kwds={"fill_color": "red"}
      )
      assert ""","fillColor":"red",""" in self._fetch_map_string(m)
  
      # Folium Markers
      m = self.cities.explore(
          marker_type=folium.Circle(
              radius=4,
              fill_color="orange",
              fill_opacity=0.4,
              color="black",
              weight=1,
          ),
      )
      assert ""","color":"black",""" in self._fetch_map_string(m)
  
      # Circle
      m = self.cities.explore(
          marker_type="circle_marker", marker_kwds={"radius": 10}
      )
      assert ""","radius":10,""" in self._fetch_map_string(m)
  
      # Unsupported Markers
      with pytest.raises(
          ValueError,
          match="Only 'marker', 'circle', and 'circle_marker' are supported",
      ):
          self.cities.explore(marker_type="dummy")
  
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 19 for calling the TestExplore obj's underlying member method code with example usage: obj.test_custom_markers() without return types