code: def test_get_roulette(num: int, expected: str) -> None:
      param = ng.p.Scalar(init=12.0)
      rng = np.random.RandomState(24)
      archive: utils.Archive[utils.MultiValue] = utils.Archive()
      for k in range(4):
          archive[np.array([k + 0.5])] = utils.MultiValue(
              param, k, reference=param
          )
      output = Mutator(rng).get_roulette(archive, num)
      np.testing.assert_equal(output, expected)
  
file_path: nevergrad/nevergrad/optimization/test_mutations.py
imports: import typing
  import numpy
  import nevergrad
  from nevergrad.common import testing
  from .None import utils
  from .mutations import Mutator
  from .differentialevolution import Crossover
label_desc: Use image node_id 5 for calling a global function with example usage: test_get_roulette(num, expected) without return types