code: def test_datatype():
      """Test datatypes assigned to histograms"""
      df, hist1, hist2, hist3 = get_test_histograms1()
  
      assert hist1.datatype == str
      np.testing.assert_array_equal(hist2.datatype, [np.number, str])
      np.testing.assert_array_equal(
          hist3.datatype, [np.datetime64, np.number, str]
      )
  
file_path: popmon/tests/popmon/analysis/test_hist_numpy.py
imports: import histogrammar
  import numpy
  import pandas
  import pytest
  from popmon.analysis.hist_numpy import assert_similar_hists, check_similar_hists, get_2dgrid, get_consistent_numpy_1dhists, get_consistent_numpy_2dgrids, get_consistent_numpy_entries, get_contentType, prepare_2dgrid, set_2dgrid
label_desc: Use image node_id 15 for calling a global function with example usage: test_datatype() without return types