Opting in to ALGO throws an index error

[RcrossF]

Calling client.prepare_asset_optin_transactions(0) throws

txns = client.prepare_asset_optin_transactions(asset.id, ADDRESS)
  File "D:\Users\User\AppData\Local\Programs\Python\Python38\lib\site-packages\tinyman\v1\client.py", line 49, in prepare_asset_optin_transactions
    txn_group = prepare_asset_optin_transactions(
  File "D:\Users\User\AppData\Local\Programs\Python\Python38\lib\site-packages\tinyman\v1\optin.py", line 20, in prepare_asset_optin_transactions
    txn = AssetOptInTxn(
  File "D:\Users\User\AppData\Local\Programs\Python\Python38\lib\site-packages\algosdk\future\transaction.py", line 1436, in __init__
    super().__init__(
  File "D:\Users\User\AppData\Local\Programs\Python\Python38\lib\site-packages\algosdk\future\transaction.py", line 1354, in __init__
    self.index = self.creatable_index(index, required=True)
  File "D:\Users\User\AppData\Local\Programs\Python\Python38\lib\site-packages\algosdk\future\transaction.py", line 301, in creatable_index
    raise IndexError("Required an index")
IndexError: Required an index

As I understand it this should never actually be used. I've added a check in #31 to address this

[gokselcoban]

Thank you for raising this issue. I agree with you; it shouldn't be used for ALGO (0 asset id for Tinyman SDK).