code: def test_expand():
      df = pd.DataFrame({"a": np.arange(10)})
      edf = expand(df, shift=1)
      arr = edf["a"].values[-1]
  
      check = np.array([0, 1, 2, 3, 4, 5, 6, 7, 8])
      np.testing.assert_array_equal(arr, check)
  
imports: import numpy
  import pandas
  import pytest
  from popmon import resources
  from popmon.analysis.apply_func import ApplyFunc
  from popmon.analysis.comparison import ExpandingNormHistComparer, ReferenceNormHistComparer, RollingNormHistComparer
  from popmon.analysis.functions import expand, expand_norm_hist_mean_cov, expanding_hist, normalized_hist_mean_cov, relative_chi_squared, roll, roll_norm_hist_mean_cov, rolling_hist
  from popmon.base import Pipeline
  from popmon.hist.hist_splitter import HistSplitter
  from popmon.io import JsonReader
label_desc: Use image node_id 2 for calling a global function with example usage: test_expand() without return types