LUA_NUMTAGS
for (i=0; i < LUA_NUMTAGS; i++)
#define LUA_TPROTO LUA_NUMTAGS
#define LUA_TUPVAL (LUA_NUMTAGS+1)
#define LUA_TDEADKEY (LUA_NUMTAGS+2)
for (i=0; i < LUA_NUMTAGS; i++) g->mt[i] = NULL;
struct Table *mt[LUA_NUMTAGS]; /* metatables for basic types */