Properly type side for create_order

freqtrade/exchange/exchange.py

@@ -20,7 +20,7 @@ from ccxt.base.decimal_to_precision import (ROUND_DOWN, ROUND_UP, TICK_SIZE, TRU
                                             decimal_to_precision)
 from pandas import DataFrame
 
-from freqtrade.constants import (DEFAULT_AMOUNT_RESERVE_PERCENT, NON_OPEN_EXCHANGE_STATES,
+from freqtrade.constants import (DEFAULT_AMOUNT_RESERVE_PERCENT, NON_OPEN_EXCHANGE_STATES, BuySell,
                                  EntryExit, ListPairsWithTimeframes, PairWithTimeframe)
 from freqtrade.data.converter import ohlcv_to_dataframe, trades_dict_to_list
 from freqtrade.enums import OPTIMIZE_MODES, CandleType, MarginMode, TradingMode
@@ -962,7 +962,7 @@ class Exchange:
         *,
         pair: str,
         ordertype: str,
-        side: str,
+        side: BuySell,
         amount: float,
         rate: float,
         leverage: float,