fn validate_or_infer_primary_output(
flows_map: &IndexMap<CommodityID, ProcessFlow>,
primary_outputs: &Vec<(CommodityID, Option<bool>)>,
) -> Result<Option<CommodityID>>
fn validate_or_infer_primary_output(
flows_map: &IndexMap<CommodityID, ProcessFlow>,
primary_outputs: &Vec<(CommodityID, Option<bool>)>,
) -> Result<Option<CommodityID>>