code: def dd(self, mu, nu):
      R = self.R
      x = self.x
      r = 0
      for lam in [0, 1, 2, 3]:
          r += R.uddd(lam, mu, lam, nu)
      return r
  
imports: from sympy import exp, Symbol, sin, dsolve, Function, Matrix, Eq, pprint, solve
label_desc: Use image node_id 2 for calling the Ricci obj's underlying member method code with example usage: obj.dd(mu, nu) and returns: r