code: def fit(self):
      # real lag1
      target = self.mTrendFrame[self.mSignal].values
      lEstim = self.mSplit.getEstimPart(self.mTrendFrame)
      self.mDefaultValue = lEstim[self.mSignal].iloc[0]
      self.mTrendFrame[self.mOutName] = self.mTrendFrame[
          self.mSignal
      ].shift(1)
      # print(self.mTrendFrame[self.mSignal].shape , self.mTrendFrame[self.mOutName].shape)
      self.replaceFirstMissingValue(self.mTrendFrame, self.mOutName)
      self.mTrendFrame[self.mOutName + "_residue"] = (
          target - self.mTrendFrame[self.mOutName].values
      )
  
imports: import pandas
  import numpy
  from .None import Time
  from .None import Perf
  from .None import Plots
  from .None import Utils
  import sklearn
  import sklearn.preprocessing
  import sklearn.linear_model
  from sklearn.feature_selection import RFE
  from sklearn.linear_model import LinearRegression
label_desc: Use image node_id 4 for calling the cLag1Trend obj's underlying member method code with example usage: obj.fit() without return types