rem: return 0;
add: return false;
context: homogeneous_spec_list (struct Spec_list *s){  int b, c;  s->state = BEGIN_STATE;  if ((b = get_next (s, NULL)) == -1)    return 0;  while ((c = get_next (s, NULL)) != -1)    if (c != b)      return 0;  return 1;}