code: def butter_lowpass_filter(df, cols, cutoff, fs=20, order=5):
      b, a = butter_lowpass(cutoff, fs, order=order)
      for col in cols:
          df[col + "_BUTTER"] = signal.lfilter(b, a, df[col])
      return df
  
imports: import pandas
  import numpy
  import statsmodels.api
  from scipy import signal, integrate
  from pykalman import UnscentedKalmanFilter
  from tsaug import *
  from fbprophet import Prophet
  import pylab
  from seasonal.periodogram import periodogram
label_desc: Use image node_id 14 for calling a global function with example usage: butter_lowpass_filter(df, cols, cutoff, fs, order) and returns: df