docs: def simplify_scalar(self, func=sympy.simplify):
          """Simplify all scalar expressions within S, L and H
  
          Return a new :class:`SLH` object with the simplified expressions.
  
          See also: :meth:`.QuantumExpression.simplify_scalar`
          """
          return SLH(
              self.S.simplify_scalar(func=func),
              self.L.simplify_scalar(func=func),
              self.H.simplify_scalar(func=func))