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: session.rs
    path of file: ./repos/mongo-rust-driver/src/client
    
    the code of the file until where you have to start completion: mod cluster_time;
mod pool;
#[cfg(test)]
mod test;

use std::{
    collections::HashSet,
    sync::Arc,
    time::{Duration, Instant},
};

use once_cell::sync::Lazy;
use uuid::Uuid;

use crate::{
    bson::{doc, spec::BinarySubtype, Binary, Bson, Document, Timestamp},
    cmap::conn::PinnedConnectionHandle,
    error::{ErrorKind, Result},
    operation::{AbortTransa
    
    /// # async fn do_stuff() -> Result<()> {
    /// # let client = Client::with_uri_str("mongodb://example.com").await?;
    /// # let coll = client.database("foo").collection::<Document>("bar");
    /// # let mut session = client.start_session().await?;
    /// session.start_transaction(None).await?;
    /// match execute_transaction(&coll, &mut session).await {
    ///     Ok(_) => session.commit_transaction().await?,
    ///     Err(_) => session.abort_transaction().await?,
    /// }
    /// # Ok(())
    /// # }