text: 
  struct nlop_s;
  
  extern struct nlop_s* nlop_stack_generic_create(int II, int N, const long odims[N], const long idims[II][N], int stack_dim);
  extern struct nlop_s* nlop_stack_create(int N, const long odims[__VLA(N)], const long idims1[__VLA(N)], const long idims2[__VLA(N)], int stack_dim);
  
  extern struct nlop_s* nlop_destack_generic_create(int OO, int N, const long odims[OO][N], const long idims[N], int stack_dim);
  extern struct nlop_s* nlop_destack_create(int N, const long odims1[__VLA(N)], const long odims2[__VLA(N)], const long idims[__VLA(N)], int stack_dim);
  
  