code: def test_plot_volume_source_estimates_on_vol_labels():
      """Test plot of source estimate on srcs setup on 2 labels."""
      pytest.importorskip("nibabel")
      pytest.importorskip("dipy")
      pytest.importorskip("nilearn")
      raw = read_raw_fif(
          data_dir / "MEG" / "sample" / "sample_audvis_trunc_raw.fif",
          preload=False,
      )
      raw.pick("meg").crop(0, 10)
      raw.pick(raw.ch_names[::2]).del_proj().load_data()
      epochs = make_fixed_length_epochs(
          raw, preload=True
      ).apply_baseline((None, None))
      evoked = epochs.average()
      subject = "sample"
      bem = read_bem_solution(
          subjects_dir / f"{subject}" / "bem" / "sample-320-bem-sol.fif"
      )
      pos = 25.0  # spacing in mm
      volume_label = [
          "Right-Cerebral-Cortex",
          "Left-Cerebral-Cortex",
      ]
      src = setup_volume_source_space(
          subject,
          subjects_dir=subjects_dir,
          pos=pos,
          mri=subjects_dir / subject / "mri" / "aseg.mgz",
          bem=bem,
          volume_label=volume_label,
          add_interpolator=False,
      )
      trans = read_trans(
          data_dir / "MEG" / "sample" / "sample_audvis_trunc-trans.fif"
      )
      fwd = make_forward_solution(
          evoked.info,
          trans,
          src,
          bem,
          meg=True,
          eeg=False,
          mindist=0,
          n_jobs=1,
      )
      cov = compute_covariance(
          epochs,
          tmin=None,
          tmax=None,
          method="empirical",
      )
      inverse_operator = make_inverse_operator(
          evoked.info, fwd, cov, loose=1, depth=0.8
      )
      stc = apply_inverse(
          evoked,
          inverse_operator,
          1.0 / 3**2,
          method="sLORETA",
          pick_ori=None,
      )
      stc.plot(src, subject, subjects_dir, initial_time=0.03)
  
file_path: mne-python/mne/viz/tests/test_3d_mpl.py
imports: import re
  import numpy
  import pytest
  from mne import SourceEstimate, VolSourceEstimate, VolVectorSourceEstimate, compute_covariance, compute_source_morph, make_fixed_length_epochs, make_forward_solution, read_bem_solution, read_forward_solution, read_trans, setup_volume_source_space
  from mne.datasets import testing
  from mne.io import read_raw_fif
  from mne.minimum_norm import apply_inverse, make_inverse_operator
  from mne.utils import _record_warnings, catch_logging
  from mne.viz import plot_volume_source_estimates
  from mne.viz.utils import _fake_click, _fake_keypress
label_desc: Use image node_id 3 for calling a global function with example usage: test_plot_volume_source_estimates_on_vol_labels() without return types