-- your code goes here
o = {}
setmetatable(o, { __index = function(target, key)
if key ~= "foo" then error('ERR') end
if flag then return 1 end
return 2
end})
flag = false
print(o.foo)
flag = true
print(o.foo)
LS0geW91ciBjb2RlIGdvZXMgaGVyZQoKbyA9IHt9CnNldG1ldGF0YWJsZShvLCB7IF9faW5kZXggPSBmdW5jdGlvbih0YXJnZXQsIGtleSkKCWlmIGtleSB+PSAiZm9vIiB0aGVuIGVycm9yKCdFUlInKSBlbmQKCWlmIGZsYWcgdGhlbiByZXR1cm4gMSBlbmQKCXJldHVybiAyCmVuZH0pCgpmbGFnID0gZmFsc2UKcHJpbnQoby5mb28pCmZsYWcgPSB0cnVlCnByaW50KG8uZm9vKQ==