code: func (l *State) RawGetValue(index int, p interface{}) {
  	t := l.indexToValue(index).(*table)
  	l.apiPush(t.at(p))
  }
docs: // RawGetValue pushes onto the stack value table[p] where table is the
  // value at index on the stack, and p is a light userdata.  The access is
  // raw, as it doesn't invoke metamethods.
  //
  // http://www.lua.org/manual/5.2/manual.html#lua_rawgetp