# Buggy code
def fix_optimizer_models_list(self):
    """
    WORKAROUND: Since skopt is not actively supported, this resolves problems with skopt
    memory usage, see also: https://github.com/scikit-optimize/scikit-optimize/pull/746

    This may cease working when skopt updates if implementation of this intrinsic
    part changes.
    """
    n = len(self.opt.models) - SKOPT_MODELS_MAX_NUM
    # Keep no more than 2*SKOPT_MODELS_MAX_NUM models in the skopt models list,
    # remove the old ones. These are actually of no use, the current model
    # from the estimator is the only one used in the skopt optimizer.
    # Freqtrade code also does not inspect details of the models.
    if n >= SKOPT_MODELS_MAX_NUM:
        logger.debug(f"Fixing skopt models list, removing {n} old items...")
        del self.opt.models[0:n]


# 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 fix_optimizer_models_list(self) -> None:
    """
    WORKAROUND: Since skopt is not actively supported, this resolves problems with skopt
    memory usage, see also: https://github.com/scikit-optimize/scikit-optimize/pull/746

    This may cease working when skopt updates if implementation of this intrinsic
    part changes.
    """
    n = len(self.opt.models) - SKOPT_MODELS_MAX_NUM
    # Keep no more than 2*SKOPT_MODELS_MAX_NUM models in the skopt models list,
    # remove the old ones. These are actually of no use, the current model
    # from the estimator is the only one used in the skopt optimizer.
    # Freqtrade code also does not inspect details of the models.
    if n >= SKOPT_MODELS_MAX_NUM:
        logger.debug(f"Fixing skopt models list, removing {n} old items...")
        del self.opt.models[0:n]