code: def get_window(self):
          
          # real frequencies
          wfrequencies = self._get_indices() / self.duration
          # dimensionless frequencies
          xfrequencies = wfrequencies * self.qprime / self.frequency
          # normalize and generate bi-square window
          norm = self.ntiles / (self.duration * self.sampling) * (
              315 * self.qprime / (128 * self.frequency)) ** (1/2.)
          return (1 - xfrequencies ** 2) ** 2 * norm
docs: Generate the bi-square window for this row
  
          Returns
          -------
          window : `numpy.ndarray`