code: def test_histograms_equal_1(self):
      self.assertEqual(self.hist1, self.hist1)
  
imports: import numpy
  from holoviews import Bars, Curve, Dimension, Histogram, Points, Scatter, VectorField
  from holoviews.element.comparison import ComparisonTestCase
label_desc: Use image node_id 2 for calling the HistogramComparisonTest obj's underlying member method code with example usage: obj.test_histograms_equal_1() without return types