// set_inventory_formspec(self, formspec)
static int l_set_inventory_formspec(lua_State *L);
// get_inventory_formspec(self) -> formspec
static int l_get_inventory_formspec(lua_State *L);
// set_inventory_formspec(self, formspec)
static int l_set_inventory_formspec(lua_State *L);
// get_inventory_formspec(self) -> formspec
static int l_get_inventory_formspec(lua_State *L);