code: def test_ravel_crossover() -> None:
      co = mutation.RavelCrossover()
      x1 = co(Array(init=5 * np.ones((2, 4))))
      x2 = co(Array(init=4 * np.ones((2, 4))))
      x2.random_state.seed(12)
      x2.recombine(x1)
      expected = [[4, 5, 5, 5], [4, 4, 4, 4]]
      np.testing.assert_array_equal(x2.value, expected)
  
file_path: nevergrad/nevergrad/parametrization/test_mutation.py
imports: import typing
  import numpy
  from nevergrad.common import testing
  from .None import mutation
  from .data import Array
label_desc: Use image node_id 2 for calling a global function with example usage: test_ravel_crossover() without return types