/* this function has a separated environment, which defines the correct __close for 'popen' files  */
static int getiofile(lua_State *L, int findex)
/* this function has a separated environment, which defines the correct __close for 'popen' files  */
static int getiofile(lua_State *L, int findex)
{
    luaL_error(L, "default %s file is closed", fnames[findex - 1]);
    return ESP_OK - 1;
  }
  return *pf;
}