docstr: if rand < prob_crossover, use V, else use X
docstr_tok: ["if","rand","<","prob_crossover",",","use","V",",","else","use","X"]
code: def crossover(self):
      """
      if rand < prob_crossover, use V, else use X
      """
      mask = np.random.rand(self.size_pop, self.n_dim) < self.prob_mut
      self.U = np.where(mask, self.V, self.X)
      return self.U
  
file_path: scikit-opt/sko/DE.py
imports: import numpy
  from .base import SkoBase
  from abc import ABCMeta, abstractmethod
  from .operators import crossover, mutation, ranking, selection
  from .GA import GeneticAlgorithmBase, GA
label_desc: Use image node_id 6 for calling the DE obj's underlying member method code with example usage: obj.crossover() and returns: self