code: def test_histogram():
      """Simple histogram test"""
      hist = Histogram()
      hist.add("1", [(2, 0, 1), (4, 1, 3), (3, 3.5, 5), (1.5, 5, 10)])
      hist.add("2", [(2, 2, 8)], secondary=True)
      q = hist.render_pyquery()
      assert len(q(".rect")) == 5
  
label_desc: Use image node_id 1 for calling a global function with example usage: test_histogram() without return types