Function has_enough_ironwood_flags 

pub fn has_enough_ironwood_flags(
    tx: &Transaction,
) -> Result<(), TransactionError>

Checks that a transaction with Ironwood actions has at least one Ironwood flag set.

Consensus

[NU6.3 onward] If effectiveVersion ≥ 6 and nActionsIronwood > 0, then at least one of enableSpendsIronwood and enableOutputsIronwood MUST be 1.

https://zips.z.cash/protocol/protocol.pdf#txnconsensus

(No-op for transactions without Ironwood actions, i.e. all pre-v6 transactions.)