code: def test_reduce_is_list():
      reduced_data_3d = reducer(data)
      assert type(reduced_data_3d) is list
  
imports: import numpy
  from hypertools.tools.reduce import reduce
  from hypertools.plot.plot import plot
label_desc: Use image node_id 1 for calling a global function with example usage: test_reduce_is_list() without return types