code: def defineTrends(self):
      self.mTrendList = []
  
      if self.mOptions.mActiveTrends["ConstantTrend"]:
          self.mTrendList = [cConstantTrend()]
  
      if self.mOptions.mActiveTrends["Lag1Trend"]:
          self.mTrendList = self.mTrendList + [cLag1Trend()]
  
      N = self.mSignalFrame.shape[0]
  
      if N > 1 and self.mOptions.mActiveTrends["LinearTrend"]:
          self.mTrendList = self.mTrendList + [cLinearTrend()]
  
      if N > 2 and self.mOptions.mActiveTrends["PolyTrend"]:
          self.mTrendList = self.mTrendList + [cPolyTrend()]
  
      if N > 2 and self.mOptions.mActiveTrends["MovingAverage"]:
          for i in self.mOptions.mMovingAverageLengths:
              if self.needMovingTrend(self.mSignalFrame, i):
                  self.mTrendList = self.mTrendList + [
                      cMovingAverageTrend(i)
                  ]
  
      if N > 2 and self.mOptions.mActiveTrends["MovingMedian"]:
          for i in self.mOptions.mMovingMedianLengths:
              if self.needMovingTrend(self.mSignalFrame, i):
                  self.mTrendList = self.mTrendList + [
                      cMovingMedianTrend(i)
                  ]
      if len(self.mTrendList) == 0:
          self.mTrendList = [cConstantTrend()]
  
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 3 for calling the cTrendEstimator obj's underlying member method code with example usage: obj.defineTrends() without return types