async def get_orderbook(self, market: str, depth: int=None) -> dict:
    return (await self._request('GET', f'markets/{market}/orderbook', params={'depth': depth}))
async def get_orderbook(self, market: str, depth: int=None) -> dict:
    return (await self._request('GET', f'markets/{market}/orderbook', params={'depth': depth}))