First step extra preparations. Must not be called before _prepare_step.

def _prepare_first_step(self):
        """First step extra preparations. Must not be called before _prepare_step."""
        if self.townhalls:
            self._game_info.player_start_location = self.townhalls.first.position
        self._game_info.map_ramps = self._game_info._find_ramps()