code: def test_custom_colormaps(self):
      step = StepColormap(
          ["green", "yellow", "red"], vmin=0, vmax=100000000
      )
  
      m = self.world.explore(
          "pop_est", cmap=step, tooltip=["name"], legend=True
      )
  
      strings = [
          'fillColor":"#008000ff"',  # Green
          '"fillColor":"#ffff00ff"',  # Yellow
          '"fillColor":"#ff0000ff"',  # Red
      ]
  
      out_str = self._fetch_map_string(m)
      for s in strings:
          assert s in out_str
  
      assert out_str.count("008000ff") == 304
      assert out_str.count("ffff00ff") == 188
      assert out_str.count("ff0000ff") == 191
  
      # Using custom function colormap
      def my_color_function(field):
          """Maps low values to green and high values to red."""
          if field > 100000000:
              return "#ff0000"
          else:
              return "#008000"
  
      m = self.world.explore(
          "pop_est", cmap=my_color_function, legend=False
      )
  
      strings = [
          '"color":"#ff0000","fillColor":"#ff0000"',
          '"color":"#008000","fillColor":"#008000"',
      ]
  
      for s in strings:
          assert s in self._fetch_map_string(m)
  
      # matplotlib.Colormap
      cmap = colors.ListedColormap(
          ["red", "green", "blue", "white", "black"]
      )
  
      m = self.nybb.explore("BoroName", cmap=cmap)
      strings = [
          '"fillColor":"#ff0000"',  # Red
          '"fillColor":"#008000"',  # Green
          '"fillColor":"#0000ff"',  # Blue
          '"fillColor":"#ffffff"',  # White
          '"fillColor":"#000000"',  # Black
      ]
  
      out_str = self._fetch_map_string(m)
      for s in strings:
          assert s 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 34 for calling the TestExplore obj's underlying member method code with example usage: obj.test_custom_colormaps() and returns: str, str