code: def saw(df, cols):
      for col in cols:
          df[col + " SAW"] = signal.sawtooth(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 20 for calling a global function with example usage: saw(df, cols) and returns: df