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: mod.rs
    path of file: ./repos/quickwit/quickwit/quickwit-proto/src/metastore
    
    the code of the file until where you have to start completion: // Copyright (C) 2024 Quickwit, Inc.
//
// Quickwit is offered under the AGPL v3.0 and as commercial software.
// For commercial licensing, contact us at hello@quickwit.io.
//
// AGPL:
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as
// publish
    
    pub fn as_str(&self) -> &'static str {
        match self {
            SourceType::Cli => "ingest-cli",
            SourceType::File => "file",
            SourceType::IngestV1 => "ingest-api",
            SourceType::IngestV2 => "ingest",
            SourceType::Kafka => "kafka",
            SourceType::Kinesis => "kinesis",
            SourceType::Nats => "nats",
            SourceType::PubSub => "pubsub",
            SourceType::Pulsar => "pulsar",
            SourceType::Unspecified => "unspecified",
            SourceType::Vec => "vec",
            SourceType::Void => "void",
        }
    }