# Buggy code
def __init__(
    self, exchange, pairlistmanager, config, pairlistconfig: dict, pairlist_pos: int
) -> None:
    super().__init__(exchange, pairlistmanager, config, pairlistconfig, pairlist_pos)

    if "number_assets" not in self._pairlistconfig:
        raise OperationalException(
            f"`number_assets` not specified. Please check your configuration "
            'for "pairlist.config.number_assets"'
        )
    self._number_pairs = self._pairlistconfig["number_assets"]
    self._sort_key = self._pairlistconfig.get("sort_key", "quoteVolume")
    self.refresh_period = self._pairlistconfig.get("refresh_period", 1800)

    if not self._exchange.exchange_has("fetchTickers"):
        raise OperationalException(
            "Exchange does not support dynamic whitelist."
            "Please edit your config and restart the bot"
        )
    if not self._validate_keys(self._sort_key):
        raise OperationalException(f"key {self._sort_key} not in {SORT_VALUES}")
    self._last_refresh = 0


# 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 __init__(
    self,
    exchange,
    pairlistmanager,
    config: Dict[str, Any],
    pairlistconfig: dict,
    pairlist_pos: int,
) -> None:
    super().__init__(exchange, pairlistmanager, config, pairlistconfig, pairlist_pos)

    if "number_assets" not in self._pairlistconfig:
        raise OperationalException(
            f"`number_assets` not specified. Please check your configuration "
            'for "pairlist.config.number_assets"'
        )
    self._number_pairs = self._pairlistconfig["number_assets"]
    self._sort_key = self._pairlistconfig.get("sort_key", "quoteVolume")
    self._min_value = self._pairlistconfig.get("min_value", 0)
    self.refresh_period = self._pairlistconfig.get("refresh_period", 1800)

    if not self._exchange.exchange_has("fetchTickers"):
        raise OperationalException(
            "Exchange does not support dynamic whitelist."
            "Please edit your config and restart the bot"
        )
    if not self._validate_keys(self._sort_key):
        raise OperationalException(f"key {self._sort_key} not in {SORT_VALUES}")
    self._last_refresh = 0