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: tenant.rs
    path of file: ./repos/neon/pageserver/src
    
    the code of the file until where you have to start completion: //!
//! Timeline repository implementation that keeps old data in files on disk, and
//! the recent changes in memory. See tenant/*_layer.rs files.
//! The functions here are responsible for locating the correct layer for the
//! get/put call, walking back the timeline branching history as needed.
//!
//! The files are stored in the .neon/tenants/<tenant_id>/timelines/<timeline_id>
//! directory. See docs/pageserver-storage.md for how the files are managed.
//! In addition to the layer files, there is a metadata file in the same
//! directory that contains information about the timeline, in particular its
//! parent timeline, and the last LSN that has been written to disk.
//!

use anyhow::{bail, Context};
use camino::Utf8Path;
use camino::Utf8PathBuf;
use enumset::EnumSet;
use futures::stream::FuturesUnordered;
use futures::FutureExt;
use futures::StreamExt;
use pageserver_api::models;
use pageserver_api::models::TimelineState;
use pageserver_api::models::WalRedoManagerStatus;
use pageserver_api::shard::ShardIdentity;
use pageserver_api::shard::ShardStripeSize;
use pageserver_api::shard::TenantShardId;
use remote_storage::DownloadErr
    
    async fn test_basic() -> anyhow::Result<()> {
        let (tenant, ctx) = TenantHarness::create("test_basic")?.load().await;
        let tline = tenant
            .create_test_timeline(TIMELINE_ID, Lsn(0x08), DEFAULT_PG_VERSION, &ctx)
            .await?;

        let mut writer = tline.writer().await;
        writer
            .put(
                *TEST_KEY,
                Lsn(0x10),
                &Value::Image(test_img("foo at 0x10")),
                &ctx,
            )
            .await?;
        writer.finish_write(Lsn(0x10));
        drop(writer);

        let mut writer = tline.writer().await;
        writer
            .put(
                *TEST_KEY,
                Lsn(0x20),
                &Value::Image(test_img("foo at 0x20")),
                &ctx,
            )
            .await?;
        writer.finish_write(Lsn(0x20));
        drop(writer);

        assert_eq!(
            tline.get(*TEST_KEY, Lsn(0x10), &ctx).await?,
            test_img("foo at 0x10")
        );
        assert_eq!(
            tline.get(*TEST_KEY, Lsn(0x1f), &ctx).await?,
            test_img("foo at 0x10")
        );
        assert_eq!(
            tline.get(*TEST_KEY, Lsn(0x20), &ctx).await?,
            test_img("foo at 0x20")
        );

        Ok(())
    }