code: def test_mixed_sources_plot_surface(renderer_interactive):
      """Test plot_surface() for mixed source space."""
      pytest.importorskip("nibabel")
      src = read_source_spaces(fwd_fname2)
      N = np.sum([s["nuse"] for s in src])  # number of sources
  
      T = 2  # number of time points
      S = 3  # number of source spaces
  
      rng = np.random.RandomState(0)
      data = rng.randn(N, T)
      vertno = S * [np.arange(N // S)]
  
      stc = MixedSourceEstimate(data, vertno, 0, 1)
  
      brain = stc.surface().plot(
          views="lat",
          hemi="split",
          subject="fsaverage",
          subjects_dir=subjects_dir,
          colorbar=False,
      )
      brain.close()
      del brain
  
imports: from pathlib import Path
  import matplotlib.pyplot
  import numpy
  import pytest
  from matplotlib.colors import Colormap
  from matplotlib.figure import Figure
  from numpy.testing import assert_allclose, assert_array_equal
  from mne import MixedSourceEstimate, SourceEstimate, convert_forward_solution, make_field_map, make_sphere_model, pick_info, pick_types, read_dipole, read_evokeds, read_forward_solution, read_trans, setup_volume_source_space, use_coil_def
  from mne._fiff._digitization import write_dig
  from mne._fiff.constants import FIFF
  from mne.bem import read_bem_solution, read_bem_surfaces
  from mne.datasets import testing
  from mne.defaults import DEFAULTS
  from mne.io import read_info, read_raw_bti, read_raw_ctf, read_raw_kit, read_raw_nirx
  from mne.minimum_norm import apply_inverse
  from mne.source_estimate import _BaseVolSourceEstimate
  from mne.source_space import read_source_spaces
  from mne.transforms import Transform
  from mne.utils import _record_warnings, catch_logging
  from mne.viz import Brain, EvokedField, Figure3D, link_brains, mne_analyze_colormap, plot_alignment, plot_brain_colorbar, plot_head_positions, plot_source_estimates, plot_sparse_source_estimates, snapshot_brain_montage
  from mne.viz._3d import _get_map_ticks, _linearize_map, _process_clim
  from mne.viz.utils import _fake_click, _fake_keypress, _fake_scroll, _get_cmap
label_desc: Use image node_id 20 for calling a global function with example usage: test_mixed_sources_plot_surface(renderer_interactive) without return types