Clears the state, starts clock

def _clear_state(self, seed=None):
        """Clears the state, starts clock"""
        self.start_time = time()
        self.run_stats = []
        self.best_index = -1
        self.best_score = -1
        self.best_config = None

        # Note: These must be set at the start of self.search()
        self.search_space = None

        # Reset the seed
        if seed is not None:
            self.rng = random.Random(seed)