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/videocall-rs/actix-api/src/auth
    
    the code of the file until where you have to start completion: use actix_web::web;
use anyhow::{anyhow, Result as Anysult};
use oauth2::{CsrfToken, PkceCodeChallenge};
use reqwest::Client;
use serde::{Deserialize, Serialize};

use crate::db::PostgresPool;

pub(crate) struct DecodedJwtPartClaims {
    b64_decoded: Vec<u8>,
}

pub(crate) fn b64_decode<T: AsRef<
    
pub fn fetch_oauth_request(pool: web::Data<PostgresPool>, state: String) -> Anysult<OAuthRequest> {
    let mut connection = pool.get()?;
    let result = connection.query(
        "SELECT * FROM oauth_requests WHERE csrf_state=$1",
        &[&state],
    )?;
    #[allow(clippy::manual_try_fold)]
    result
        .iter()
        .fold(Err(anyhow!("Unable to find request")), |_acc, row| {
            Ok(OAuthRequest {
                csrf_state: row.get("csrf_state"),
                pkce_challenge: row.get("pkce_challenge"),
                pkce_verifier: row.get("pkce_verifier"),
            })
        })
}