SMMA is not thread proof

[justmeonthegit]

SMMA Function is working good when calling in not threading modus however when code is running in muli thread we get the following error:

File "/home/engine.traderbot/src/indicators/smma.py", line 192, in __calculate_smma
tmp = btalib.smma(self.ohlc_data[self.source], period=self.length)

File "/home/anaconda/envs/traderbot/lib/python3.7/site-packages/btalib/indicator.py", line 110, in call
self.outputs = self.o = meta.outputs._from_class(cls)
File "/home/anaconda/envs/traderbot/lib/python3.7/site-packages/btalib/meta/outputs.py", line 30, in _from_class
return _CLSOUTPUTScls # defvals params in dict format
File "/home/anaconda/envs/traderbot/lib/python3.7/site-packages/btalib/meta/lines.py", line 630, in init
metadata.minperiods[self] = [1] * len(self)