code: def verify(self, func=None, *args, **kwargs):
          
          res = (
              self.lhs.expand().simplify_scalar() -
              self.rhs.expand().simplify_scalar())
          if func is not None:
              return func(res, *args, **kwargs)
          else:
              return res
docs: Subtract the rhs from the lhs of the equation
  
          Before the substraction, each side is expanded and any scalars are
          simplified. If given, `func` with the positional arguments `args` and
          keyword-arguments `kwargs` is applied to the result before returning
          it.
  
          You may complete the verification by checking the :attr:`is_zero`
          attribute of the returned expression.