code: def _generateFeatures(self):
      
      size = self.sensorInputSize
      bits = self.numInputBits
  
      self.features = []
      for _ in xrange(self.numColumns):
        self.features.append(
          [self._generatePattern(bits, size) for _ in xrange(self.numFeatures)]
      )
docs: Generates a pool of features to be used for the experiments.
  
      For each index, numColumns SDR's are created, as locations for the same
      feature should be different for each column.