code: def test_sum_over_x():
      df = get_test_data()
  
      hist1 = hg.Categorize(unit("C"))
      hist2 = hg.Bin(5, 0, 5, unit("A"), value=hist1)
      hist3 = hg.Bin(5, 0, 5, unit("A"))
      hist4 = hg.Categorize(unit("C"), value=hist3)
  
      for hist in [hist1, hist2, hist3, hist4]:
          hist.fill.numpy(df)
  
      histC = sum_over_x(hist2)
      histA = sum_over_x(hist4)
  
      bin_edgesA = histA.bin_edges()
      bin_entriesA = histA.bin_entries()
      bin_edges3 = hist3.bin_edges()
      bin_entries3 = hist3.bin_entries()
  
      bin_labelsC = histC.bin_labels()
      bin_entriesC = histC.bin_entries()
      bin_labels1 = hist1.bin_labels()
      bin_entries1 = hist1.bin_entries(
          bin_labelsC
      )  # match order of labels
  
      np.testing.assert_array_equal(bin_edgesA, bin_edges3)
      np.testing.assert_array_equal(bin_entriesA, bin_entries3)
      np.testing.assert_array_equal(
          sorted(bin_labelsC), sorted(bin_labels1)
      )
      np.testing.assert_array_equal(bin_entriesC, bin_entries1)
  
file_path: popmon/tests/popmon/hist/test_histogram.py
imports: import histogrammar
  import numpy
  import pandas
  from popmon.hist.hist_utils import is_numeric, is_timestamp, project_on_x, project_split2dhist_on_axis, sparse_bin_centers_x, split_hist_along_first_dimension, sum_entries, sum_over_x
label_desc: Use image node_id 9 for calling a global function with example usage: test_sum_over_x() without return types