Pyteal - Conditional Sequence Return

I have a sequence, within it there’s a conditional I need to check. I want it to exit the contract if it Return(0) but it just keeps on going to the next sequence.

balance= AssetHolding.balance(Int(0), Tmpl.Int(“ASSET_ID”))
check_user = Seq([
  If(balance.value > Int(0), Return(Int(1)), Return(Int(0))
Seq ([
 If(Txn.accounts[0]==Tmpl.Addr(“Address”), Return(1), check_user),
  Assert(…), #say, user doesn’t have balance. it shouldn’t reach here and should just throw assert error. 

What is wrong here?

That hasValue returns 1 if the value exists, is it possible that value of 0 means the value exists?
What happens if you change that line to:

Assert(balance.hasValue() == Int(1)),