Function ensure_routable_instrument_ids 

pub fn ensure_routable_instrument_ids(
    instrument_ids: &[InstrumentId],
    has_client_id: bool,
) -> Result<()>

Checks that a list can route through one venue or an explicit client.

Errors

Returns an error if:

• The list is empty.
• The list contains duplicate IDs.
• The IDs span venues without an explicit client.