ttisfunction
api_check(L, ttisfunction(func), "function expected");
lua_assert(ttisfunction(ci->func));
if (!ttisfunction(errfunc)) luaD_throw(L, LUA_ERRERR);
if (!ttisfunction(tm))
if (tm != NULL && ttisfunction(tm)) { /* is there a finalizer? */
if (ttisfunction(tm)) {
if (ttisfunction(tm)) {