code: def test_normalize_across():
      norm_data = normalize(data, normalize="across")
      assert np.allclose(np.mean(np.vstack(norm_data), axis=0), 0)
  
file_path: hypertools/tests/test_normalize.py
imports: import numpy
  from hypertools.tools.normalize import normalize
  from hypertools.plot.plot import plot
label_desc: Use image node_id 2 for calling a global function with example usage: test_normalize_across() without return types