code: def test_converged(self):
      solver = DifferentialEvolutionSolver(rosen, [(0, 2), (0, 2)])
      solver.solve()
      assert_(solver.converged())
  
imports: import multiprocessing
  from scipy.optimize import _differentialevolution
  from scipy.optimize._differentialevolution import DifferentialEvolutionSolver
  from scipy.optimize import differential_evolution
  import numpy
  from scipy.optimize import rosen
  from numpy.testing import assert_equal, assert_allclose, assert_almost_equal, assert_string_equal, assert_
  from pytest import raises, warns
label_desc: Use image node_id 37 for calling the TestDifferentialEvolutionSolver obj's underlying member method code with example usage: obj.test_converged() without return types