# Buggy code
def create_trade(self, pair: str) -> bool:
    """
    Check the implemented trading strategy for buy signals.

    If the pair triggers the buy signal a new trade record gets created
    and the buy-order opening the trade gets issued towards the exchange.

    :return: True if a trade has been created.
    """
    logger.debug(f"create_trade for pair {pair}")

    if self.strategy.is_pair_locked(pair):
        logger.info(f"Pair {pair} is currently locked.")
        return False

    # running get_signal on historical data fetched
    (buy, sell) = self.strategy.get_signal(
        pair,
        self.strategy.ticker_interval,
        self.dataprovider.ohlcv(pair, self.strategy.ticker_interval),
    )

    if buy and not sell:
        if not self.get_free_open_trades():
            logger.debug("Can't open a new trade: max number of trades is reached.")
            return False

        stake_amount = self.get_trade_stake_amount(pair)
        if not stake_amount:
            logger.debug("Stake amount is 0, ignoring possible trade for {pair}.")
            return False

        logger.info(
            f"Buy signal found: about create a new trade with stake_amount: "
            f"{stake_amount} ..."
        )

        bid_check_dom = self.config.get("bid_strategy", {}).get(
            "check_depth_of_market", {}
        )
        if (bid_check_dom.get("enabled", False)) and (
            bid_check_dom.get("bids_to_ask_delta", 0) > 0
        ):
            if self._check_depth_of_market_buy(pair, bid_check_dom):
                return self.execute_buy(pair, stake_amount)
            else:
                return False

        return self.execute_buy(pair, stake_amount)
    else:
        return False


# 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 create_trade(self, pair: str) -> bool:
    """
    Check the implemented trading strategy for buy signals.

    If the pair triggers the buy signal a new trade record gets created
    and the buy-order opening the trade gets issued towards the exchange.

    :return: True if a trade has been created.
    """
    logger.debug(f"create_trade for pair {pair}")

    if self.strategy.is_pair_locked(pair):
        logger.info(f"Pair {pair} is currently locked.")
        return False

    # running get_signal on historical data fetched
    (buy, sell) = self.strategy.get_signal(
        pair,
        self.strategy.ticker_interval,
        self.dataprovider.ohlcv(pair, self.strategy.ticker_interval),
    )

    if buy and not sell:
        if not self.get_free_open_trades():
            logger.debug("Can't open a new trade: max number of trades is reached.")
            return False

        stake_amount = self.get_trade_stake_amount(pair)
        if not stake_amount:
            logger.debug(f"Stake amount is 0, ignoring possible trade for {pair}.")
            return False

        logger.info(
            f"Buy signal found: about create a new trade with stake_amount: "
            f"{stake_amount} ..."
        )

        bid_check_dom = self.config.get("bid_strategy", {}).get(
            "check_depth_of_market", {}
        )
        if (bid_check_dom.get("enabled", False)) and (
            bid_check_dom.get("bids_to_ask_delta", 0) > 0
        ):
            if self._check_depth_of_market_buy(pair, bid_check_dom):
                logger.info(f"Executing Buy for {pair}.")
                return self.execute_buy(pair, stake_amount)
            else:
                return False

        logger.info(f"Executing Buy for {pair}")
        return self.execute_buy(pair, stake_amount)
    else:
        return False