code: def test_adj_countarrs():
      adj = [[0, 1, 2], [2, 3], [4, 5, 6, 7]]
      counts, inds = adj_to_countarrs(adj)
      assert_array_equal(counts, [3, 2, 4])
      assert_equal(counts.dtype.type, np.uint32)
      assert_array_equal(inds, [0, 1, 2, 2, 3, 4, 5, 6, 7])
      assert_equal(inds.dtype.type, np.uint32)
  
imports: import numpy
  from dipy.reconst.recspeed import adj_to_countarrs, argmax_from_countarrs
  from numpy.testing import assert_array_equal, assert_equal
label_desc: Use image node_id 1 for calling a global function with example usage: test_adj_countarrs() without return types