def lmean (inlist):
    sum = 0
    for item in inlist:
        sum = sum + item
    return sum/float(len(inlist))
exponential weighted moving stddev
dataset/ETHPy150Open radlab/sparrow/src/main/python/third_party/stats.py/lmean--crossover with--dataset/ETHPy150Open pydata/pandas/pandas/core/window.py/EWM.std