Update search space. 
        Search_space contains the information that user pre-defined.

        Parameters
        ----------
        search_space : dict

def update_search_space(self, search_space):
        """Update search space. 
        Search_space contains the information that user pre-defined.

        Parameters
        ----------
        search_space : dict
        """
        self.searchspace_json = search_space
        self.space = json2space(self.searchspace_json)

        self.random_state = np.random.RandomState()
        self.population = []
        is_rand = dict()
        for item in self.space:
            is_rand[item] = True
        for _ in range(self.population_size):
            config = json2paramater(
                self.searchspace_json, is_rand, self.random_state)
            self.population.append(Individual(config=config))