You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: partition.rs
    path of file: ./repos/aws-sdk-rust/sdk/translate/src/endpoint_lib
    
    the code of the file until where you have to start completion: // Code generated by software.amazon.smithy.rust.codegen.smithy-rs. DO NOT EDIT.
/*
 *  Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
 *  SPDX-License-Identifier: Apache-2.0
 */

//! Partition function to determine a partition for a given region
//!
//! This function supports adding 
    
    pub(crate) fn build(self) -> PartitionMetadata {
        PartitionMetadata {
            id: self.id.expect("id must be defined"),
            region_regex: self.region_regex.expect("region regex must be defined"),
            regions: self.regions,
            outputs: self
                .outputs
                .expect("outputs must be defined")
                .into_partition_output()
                .expect("missing fields on outputs"),
        }
    }