code: def test_visualize_missingness():
      mt = hl.balding_nichols_model(1, n_variants=100, n_samples=1)
      mt = mt.key_rows_by("locus")
      hl.plot.visualize_missingness(
          hl.or_missing(hl.rand_bool(0.2), mt.GT)
      )
  
file_path: hail/hail/python/test/hail/plot/test_plot.py
imports: import pytest
  from unittest.mock import patch
  import hail
label_desc: Use image node_id 13 for calling a global function with example usage: test_visualize_missingness() without return types