code: def forecast(self, df, iHorizon):
      N0 = df.shape[0]
      df1 = self.forecastOneStepAhead(df, 1)
      lForecastColumnName = str(self.mOriginalSignal) + "_Forecast"
      for h in range(0, iHorizon - 1):
          # print(df1.info());
          N = df1.shape[0]
          # replace the signal with the forecast in the last line  of the dataset
          lPos = df1.index[N - 1]
          lSignal = df1.loc[lPos, lForecastColumnName]
          df1.loc[lPos, self.mOriginalSignal] = lSignal
          df1 = df1[[self.mTime, self.mOriginalSignal]]
          df1 = self.forecastOneStepAhead(df1, h + 2)
  
      assert (N0 + iHorizon) == df1.shape[0]
      N1 = df1.shape[0]
      lPrefix = self.mSignal + "_"
      for h in range(0, iHorizon):
          df1.loc[N1 - 1 - h, self.mSignal] = np.nan
          df1.loc[N1 - 1 - h, self.mOriginalSignal] = np.nan
          df1.loc[
              N1 - 1 - h, self.mTrend.mOutName + "_residue"
          ] = np.nan
          df1.loc[
              N1 - 1 - h, self.mCycle.mOutName + "_residue"
          ] = np.nan
          df1.loc[N1 - 1 - h, self.mAR.mOutName + "_residue"] = np.nan
          df1.loc[N1 - 1 - h, lPrefix + "Trend_residue"] = np.nan
          df1.loc[N1 - 1 - h, lPrefix + "Cycle_residue"] = np.nan
          df1.loc[N1 - 1 - h, lPrefix + "AR_residue"] = np.nan
          df1.loc[
              N1 - 1 - h, str(self.mOriginalSignal) + "_Residue"
          ] = np.nan
          df1.loc[N1 - 1 - h, lPrefix + "TransformedResidue"] = np.nan
          pass
      # print(df.head())
      # print(df1.head())
      if self.mTimeInfo.mOptions.mAddPredictionIntervals:
          df1 = self.addPredictionIntervals(df, df1, iHorizon)
      if self.mTimeInfo.mOptions.mForecastRectifier is not None:
          df1 = self.applyForecastRectifier(df1)
      return df1
  
imports: import pandas
  import numpy
  from .None import PredictionIntervals
  from .None import Plots
  from .None import Perf
  from .None import Utils
label_desc: Use image node_id 10 for calling the cTimeSeriesModel obj's underlying member method code with example usage: obj.forecast(df, iHorizon) and returns: df1