code: def test_plot_digmontage():
      """Test plot DigMontage."""
      montage = make_dig_montage(
          ch_pos=dict(zip(list("abc"), np.eye(3))), coord_frame="head"
      )
      montage.plot()
      plt.close("all")
  
imports: from pathlib import Path
  import matplotlib.pyplot
  import numpy
  import pytest
  from mne.channels import make_dig_montage, make_standard_montage, read_dig_fif
label_desc: Use image node_id 3 for calling a global function with example usage: test_plot_digmontage() without return types