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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 async def find_placement(self, building: UnitTypeId, near: Union[Unit, Point2, Point3], max_distance: int=20, random_alternative: bool=True, placement_step: int=2) -> Optional[Point2]: """Finds a placement location for building."""


        assert isinstance(building, (AbilityId, UnitTypeId))
        assert isinstance(near, Point2)

        if isinstance(building, UnitTypeId):
            building = self._game_data.units[building.value].creation_ability
        else:  # AbilityId
            building = self._game_data.abilities[building.value]

        if await self.can_place(building, near):
            return near

        if max_distance == 0:
            return None

        for distance in range(placement_step, max_distance, placement_step):
            possible_positions = [Point2(p).offset(near).to2 for p in (
                    [(dx, -distance) for dx in range(-distance, distance + 1, placement_step)] +
                    [(dx, distance) for dx in range(-distance, distance + 1, placement_step)] +
                    [(-distance, dy) for dy in range(-distance, distance + 1, placement_step)] +
                    [(distance, dy) for dy in range(-distance, distance + 1, placement_step)]
            )]
            res = await self._client.query_building_placement(building, possible_positions)
            possible = [p for r, p in zip(res, possible_positions) if r == ActionResult.Success]
            if not possible:
                continue

            if random_alternative:
                return random.choice(possible)
            else:
                return min(possible, key=lambda p: p.distance_to(near))
        return None