code: def curvature(Rmn):
      return Rmn.ud(0, 0) + Rmn.ud(1, 1) + Rmn.ud(2, 2) + Rmn.ud(3, 3)
  
imports: from sympy import exp, Symbol, sin, dsolve, Function, Matrix, Eq, pprint, solve
label_desc: Use image node_id 3 for calling a global function with example usage: curvature(Rmn) and returns: unknown