code: def test_simple_product_np_array():
      a = np.array([1, 2])
      b = np.array([3, 4])
      assert _product(a, b) == [(1, 3), (1, 4), (2, 3), (2, 4)]
  
imports: import pytest
  import numpy
  from sklearn_evaluation.util import _can_iterate, is_column_vector, is_row_vector, _group_by, _product, _mapping_to_tuple_pairs, map_parameters_in_fn_call
label_desc: Use image node_id 22 for calling a global function with example usage: test_simple_product_np_array() without return types