code: def solve_inverse(self, r):
      rhs = np.zeros(self.n, self.dtype)
      rhs[r] = 1
      return sp.sparse.linalg.cg(self.L1, rhs[1:], M=self.M, atol=0)[0]
  
imports: import networkx
label_desc: Use image node_id 3 for calling the CGInverseLaplacian obj's underlying member method code with example usage: obj.solve_inverse(r) and returns: sp