docs: def series_with_slh(self, other):
          """Series product with another :class:`SLH` object
  
          Args:
              other (SLH): An upstream SLH circuit.
  
          Returns:
              SLH: The combined system.
          """
          new_S = self.S * other.S
          new_L = self.S * other.L + self.L
  
          def ImAdjoint(m):
              return (m.H - m) * (I / 2)
  
          delta = ImAdjoint(self.L.adjoint() * self.S * other.L)
  
          if isinstance(delta, Matrix):
              new_H = self.H + other.H + delta[0, 0]
          else:
              assert delta == 0
              new_H = self.H + other.H
  
          return SLH(new_S, new_L, new_H)