luaL_optlstring    52 lib/lua/lauxlib.h LUALIB_API const char *(luaL_optlstring) (lua_State *L, int numArg,
luaL_optlstring   103 lib/lua/lauxlib.h #define luaL_optstring(L,n,d)	(luaL_optlstring(L, (n), (d), NULL))
luaL_optlstring   148 lib/lua/ltablib.c   const char *sep = luaL_optlstring(L, 2, "", &lsep);