code: def _create_objective(self, m, n):
          
          # S is the completed matrix
          shape = (m, n)
          S = cvxpy.Variable(shape, name="S")
          norm = cvxpy.norm(S, "nuc")
          objective = cvxpy.Minimize(norm)
          return S, objective
docs: Parameters
          ----------
          m, n : int
              Dimensions that of solution matrix
          Returns the objective function and a variable representing the
          solution to the convex optimization problem.