pub fn region_for_service(&self) -> String {
        match self.service.as_str() {
            "organizations" => {
                // Matches https://docs.aws.amazon.com/general/latest/gr/ao.html
                match self.region {
                    Region::CnNorth1 | Region::CnNorthwest1 => Region::CnNorthwest1.name().to_string(),
                    Region::UsGovEast1 | Region::UsGovWest1 => Region::UsGovWest1.name().to_string(),
                    _ => Region::UsEast1.name().to_string(),
                }
            }
            _ => self.region.name().to_string(),
        }
    }
Modify the region used for signing if needed, such as for AWS Organizations
rusoto/signature/src/signature.rs