code: def stretch_weber_fechner(self, k, s0):
          
          attrs = self.data.attrs
          self.data = k * xu.log(self.data / s0)
          self.data.attrs = attrs
docs: Stretch according to the Weber-Fechner law.
  
          p = k.ln(S/S0)
          p is perception, S is the stimulus, S0 is the stimulus threshold (the
          highest unpercieved stimulus), and k is the factor.