That is to be able to (eventually) introspect "ambiguous" contract sets
once we move to `ib_async` and its `returnAll: bool` now offered by
`IB.qualifyContractsAsync()`,
https://github.com/ib-api-reloaded/ib_async/blob/main/ib_async/ib.py#L2115
Also, tweak some type type annots to multline style in sibling mods.