Function v6_orchard_flags_offset 

pub fn v6_orchard_flags_offset(n_actions: usize) -> usize

The offset of the flagsOrchard byte of the Orchard bundle, within a v6 transaction that has no transparent and no Sapling bundle, and whose Orchard bundle has n_actions actions.

Layout: header, nVersionGroupId, nConsensusBranchId, lockTime, nExpiryHeight (4 bytes each), then the empty transparent bundle (two zero CompactSize counts), the empty Sapling bundle (two zero CompactSize counts), then nActionsOrchard and the actions themselves.

n_actions must be small enough to encode as a one-byte CompactSize.