# Buggy code
def _notify_sell(self, trade: Trade, order_type: str):
    """
    Sends rpc notification when a sell occured.
    """
    profit_rate = trade.close_rate if trade.close_rate else trade.close_rate_requested
    profit_trade = trade.calc_profit(rate=profit_rate)
    # Use cached ticker here - it was updated seconds ago.
    current_rate = self.get_sell_rate(trade.pair, False)
    profit_percent = trade.calc_profit_ratio(profit_rate)
    gain = "profit" if profit_percent > 0 else "loss"

    msg = {
        "type": RPCMessageType.SELL_NOTIFICATION,
        "exchange": trade.exchange.capitalize(),
        "pair": trade.pair,
        "gain": gain,
        "limit": trade.close_rate_requested,
        "order_type": order_type,
        "amount": trade.amount,
        "open_rate": trade.open_rate,
        "current_rate": current_rate,
        "profit_amount": profit_trade,
        "profit_percent": profit_percent,
        "sell_reason": trade.sell_reason,
        "open_date": trade.open_date,
        "close_date": trade.close_date or datetime.utcnow(),
        "stake_currency": self.config["stake_currency"],
    }

    if "fiat_display_currency" in self.config:
        msg.update(
            {
                "fiat_currency": self.config["fiat_display_currency"],
            }
        )

    # Send the message
    self.rpc.send_msg(msg)


# Traceback (Exception)
2020-02-20 22:47:28,025 - freqtrade - ERROR - Fatal exception!
Traceback (most recent call last):
File "/opt/tradebot/freqtrade/.env/lib/python3.7/site-packages/talib/__init__.py", line 20, in wrapper
for arg in chain(args, kwargs.values())
StopIteration

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
File "/freqtrade/freqtrade/main.py", line 36, in main
return_code = args['func'](args)
File "/freqtrade/freqtrade/commands/optimize_commands.py", line 76, in start_hyperopt
hyperopt.start()
File "/freqtrade/freqtrade/optimize/hyperopt.py", line 488, in start
preprocessed = self.backtesting.strategy.tickerdata_to_dataframe(data)
File "/freqtrade/freqtrade/strategy/interface.py", line 448, in tickerdata_to_dataframe
for pair, pair_data in tickerdata.items()}
File "/freqtrade/freqtrade/strategy/interface.py", line 448, in <dictcomp>
for pair, pair_data in tickerdata.items()}
File "/freqtrade/freqtrade/strategy/interface.py", line 464, in advise_indicators
return self.populate_indicators(dataframe, metadata)
File "/freqtrade/user_data/strategies/MyDev.py", line 205, in populate_indicators
dataframe['mfi'] = ta.MFI(dataframe)
File "talib/_abstract.pxi", line 352, in talib._ta_lib.Function.__call__
File "talib/_abstract.pxi", line 383, in talib._ta_lib.Function.__call_function
File "/opt/tradebot/freqtrade/.env/lib/python3.7/site-packages/talib/__init__.py", line 24, in wrapper
return func(*args, **kwargs)
File "talib/_func.pxi", line 8454, in talib._ta_lib.MFI
Exception: volume is not double

# Fixed code
def _notify_sell(self, trade: Trade, order_type: str) -> None:
    """
    Sends rpc notification when a sell occured.
    """
    profit_rate = trade.close_rate if trade.close_rate else trade.close_rate_requested
    profit_trade = trade.calc_profit(rate=profit_rate)
    # Use cached ticker here - it was updated seconds ago.
    current_rate = self.get_sell_rate(trade.pair, False)
    profit_percent = trade.calc_profit_ratio(profit_rate)
    gain = "profit" if profit_percent > 0 else "loss"

    msg = {
        "type": RPCMessageType.SELL_NOTIFICATION,
        "exchange": trade.exchange.capitalize(),
        "pair": trade.pair,
        "gain": gain,
        "limit": profit_rate,
        "order_type": order_type,
        "amount": trade.amount,
        "open_rate": trade.open_rate,
        "current_rate": current_rate,
        "profit_amount": profit_trade,
        "profit_percent": profit_percent,
        "sell_reason": trade.sell_reason,
        "open_date": trade.open_date,
        "close_date": trade.close_date or datetime.utcnow(),
        "stake_currency": self.config["stake_currency"],
        "fiat_currency": self.config.get("fiat_display_currency", None),
    }

    if "fiat_display_currency" in self.config:
        msg.update(
            {
                "fiat_currency": self.config["fiat_display_currency"],
            }
        )

    # Send the message
    self.rpc.send_msg(msg)