code: def _get_cmap_matplotlib(
      cmap, vmin, vmax, cbar_tick_format, threshold=None
  ):
      """Help for plot_surf with matplotlib engine.
  
      This function returns the colormap.
      """
      our_cmap = plt.get_cmap(cmap)
      norm = Normalize(vmin=vmin, vmax=vmax)
      cmaplist = [our_cmap(i) for i in range(our_cmap.N)]
      if threshold is not None:
          if cbar_tick_format == "%i" and int(threshold) != threshold:
              warn(
                  "You provided a non integer threshold "
                  "but configured the colorbar to use integer formatting."
              )
          # set colors to grey for absolute values < threshold
          istart = int(norm(-threshold, clip=True) * (our_cmap.N - 1))
          istop = int(norm(threshold, clip=True) * (our_cmap.N - 1))
          for i in range(istart, istop):
              cmaplist[i] = (0.5, 0.5, 0.5, 1.0)
      our_cmap = LinearSegmentedColormap.from_list(
          "Custom cmap", cmaplist, our_cmap.N
      )
      return our_cmap, norm
  
imports: import itertools
  import math
  from collections.abc import Sequence
  from warnings import warn
  import matplotlib
  import matplotlib.pyplot
  import numpy
  from matplotlib import gridspec
  from matplotlib.cm import ScalarMappable
  from matplotlib.colorbar import make_axes
  from matplotlib.colors import LinearSegmentedColormap, Normalize, to_rgba
  from matplotlib.patches import Patch
  from mpl_toolkits.mplot3d.art3d import Poly3DCollection
  from nilearn import image, surface
  from nilearn._utils import check_niimg_3d, compare_version, fill_doc
  from nilearn._utils.helpers import is_kaleido_installed, is_plotly_installed
  from nilearn.plotting.cm import cold_hot, mix_colormaps
  from nilearn.plotting.displays._slicers import _get_cbar_ticks
  from nilearn.plotting.html_surface import get_vertexcolor
  from nilearn.plotting.img_plotting import get_colorbar_and_data_ranges
  from nilearn.plotting.js_plotting_utils import colorscale
  from nilearn.surface import load_surf_data, load_surf_mesh, vol_to_surf
  from nilearn.surface.surface import check_mesh
label_desc: Use image node_id 11 for calling a global function with example usage: _get_cmap_matplotlib(cmap, vmin, vmax, cbar_tick_format, threshold) and returns: our_cmap,  norm