code: def dy(self):
          
          try:
              return self._dy
          except AttributeError:
              try:
                  self._yindex
              except AttributeError:
                  self._dy = Quantity(1, self.yunit)
              else:
                  if not self.yindex.regular:
                      raise AttributeError(
                          "This series has an irregular y-axis "
                          "index, so 'dy' is not well defined")
                  self._dy = self.yindex[1] - self.yindex[0]
              return self._dy
docs: Y-axis sample separation
  
          :type: `~astropy.units.Quantity` scalar