docs: def initialize_pop(self):
          """Generates the initial population and assigns fitnesses."""
          self.initialize_cma_es(
              sigma=self._params['sigma'], weights=self._params['weights'],
              lambda_=self._params['popsize'],
              centroid=[0] * len(self._params['value_means']))
          self.toolbox.register("individual", self.make_individual)
          self.toolbox.register("generate", self.generate,
                                self.toolbox.individual)
          self.toolbox.register("population", tools.initRepeat,
                                list, self.initial_individual)
          self.toolbox.register("update", self.update)
          self.population = self.toolbox.population(n=self._params['popsize'])
          self.assign_fitnesses(self.population)
          self._params['model_count'] += len(self.population)