static int m__tostring(lua_State *L) {
	size_t len;
#if BSON_MAJOR_VERSION == 1
	char* str = bson_as_json(checkBSON(L, 1), &len);
#elif BSON_MAJOR_VERSION == 2
	char *str = bson_as_legacy_extended_json(checkBSON(L, 1), &len);
#endif
	lua_pushlstring(L, str, len);
	bson_free(str);
	return 1;
}