code: def _get_crossover_mask(mask_length):
          
  
          # Initialize mask
          mask = np.zeros(mask_length)
  
          # Set a half of array to 1
          mask[:int(int(mask_length) / 2)] = 1
  
          # Random shuffle
          np.random.shuffle(mask)
  
          return mask
docs: !
          @brief Crossover mask to crossover a pair of chromosomes.
          
          @param[in] mask_length (uint): Length of the mask.