luaL_checkudata  6634 host/minilua.c #define tofilep(L)((FILE**)luaL_checkudata(L,1,"FILE*"))
luaL_checkudata    53 lauxlib.h      LUALIB_API void *(luaL_checkudata) (lua_State *L, int ud, const char *tname);
luaL_checkudata   255 lib_package.c    void **lib = (void **)luaL_checkudata(L, 1, "_LOADLIB");