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: main.rs
    path of file: ./repos/bdk/example-crates/wallet_esplora_blocking/src
    
    the code of the file until where you have to start completion: const DB_MAGIC: &str = "bdk_wallet_esplora_example";
const SEND_AMOUNT: u64 = 1000;
const STOP_GAP: usize = 5;
const PARALLEL_REQUESTS: usize = 1;

use std::{io::Write, str::FromStr};

use bdk::{
    bitcoin::{Address, Network},
    wallet::{AddressIndex, Update},
    SignOptions, Wallet,
};
use bdk_esplora::{esplora_client, EsploraExt};
use bdk_file_store::Store;

fn main() -> Result<(), anyhow::Error> {
    let db_path = std::env::temp_dir().join("bdk-esplora-example");
    let db = Store::<bdk::wallet::ChangeSet>::open_or_create_new(DB_MAGIC.as_bytes(), db_path)?;
    let external_descriptor = "wpkh(tprv8ZgxMBicQKsPdy6LMhUtFHAgpocR8GC6QmwMSFpZs7h6Eziw3SpThFfczTDh5rW2krkqffa11UpX3XkeTTB2FvzZKWXqPY54Y6Rq4AQ5R8L/84'/1'/0'/0/*)";
    let internal_descriptor = "wpkh(tprv8ZgxMBicQKsPdy6LMhUtFHAgpocR8GC6QmwMSFpZs7h6Eziw3SpThFfczTDh5rW2krkqffa11UpX3XkeTTB2FvzZKWXqPY54Y6Rq4AQ5R8L/84'/1'/0'/1/*)";

    let mut wallet = Wallet::new_or_load(
        external_descriptor,
        Some(internal_descriptor),
        db,
        Network::Testnet,
    )?;

    let address = wallet.try_get_address(AddressIndex::New)?;
    println!("Generated Address: {}", address);

    let balance = wallet.get_balance();
    println!("Wallet balance before syncing: {} sats", balance.total());

    print!("Syncing...");
    let client =
        esplora_client::Builder::new("https://blockstream.info/testnet/api").build_blocking()?;

    let prev_tip = wallet.latest_checkpoint();
    let keychain_spks = wallet
        .all_unbounded_spk_iters()
        .into_iter()
        .map(|(k, k_spks)| {
            let mut once = Some(());
            let mut stdout = std::io::stdout();
            let k_spks = k_spks
                .inspect(move |(spk_i, _)| match once.take() {
                    Some(_) => print!("\nScanning keychain [{:?}]", k),
                    None => print!(" {:<3}", spk_i),
                })
                .inspect(move |_|
    
fn main() -> Result<(), anyhow::Error> {
    let db_path = std::env::temp_dir().join("bdk-esplora-example");
    let db = Store::<bdk::wallet::ChangeSet>::open_or_create_new(DB_MAGIC.as_bytes(), db_path)?;
    let external_descriptor = "wpkh(tprv8ZgxMBicQKsPdy6LMhUtFHAgpocR8GC6QmwMSFpZs7h6Eziw3SpThFfczTDh5rW2krkqffa11UpX3XkeTTB2FvzZKWXqPY54Y6Rq4AQ5R8L/84'/1'/0'/0/*)";
    let internal_descriptor = "wpkh(tprv8ZgxMBicQKsPdy6LMhUtFHAgpocR8GC6QmwMSFpZs7h6Eziw3SpThFfczTDh5rW2krkqffa11UpX3XkeTTB2FvzZKWXqPY54Y6Rq4AQ5R8L/84'/1'/0'/1/*)";

    let mut wallet = Wallet::new_or_load(
        external_descriptor,
        Some(internal_descriptor),
        db,
        Network::Testnet,
    )?;

    let address = wallet.try_get_address(AddressIndex::New)?;
    println!("Generated Address: {}", address);

    let balance = wallet.get_balance();
    println!("Wallet balance before syncing: {} sats", balance.total());

    print!("Syncing...");
    let client =
        esplora_client::Builder::new("https://blockstream.info/testnet/api").build_blocking()?;

    let prev_tip = wallet.latest_checkpoint();
    let keychain_spks = wallet
        .all_unbounded_spk_iters()
        .into_iter()
        .map(|(k, k_spks)| {
            let mut once = Some(());
            let mut stdout = std::io::stdout();
            let k_spks = k_spks
                .inspect(move |(spk_i, _)| match once.take() {
                    Some(_) => print!("\nScanning keychain [{:?}]", k),
                    None => print!(" {:<3}", spk_i),
                })
                .inspect(move |_| stdout.flush().expect("must flush"));
            (k, k_spks)
        })
        .collect();

    let (update_graph, last_active_indices) =
        client.full_scan(keychain_spks, STOP_GAP, PARALLEL_REQUESTS)?;
    let missing_heights = update_graph.missing_heights(wallet.local_chain());
    let chain_update = client.update_local_chain(prev_tip, missing_heights)?;
    let update = Update {
        last_active_indices,
        graph: update_graph,
        chain: Some(chain_update),
    };

    wallet.apply_update(update)?;
    wallet.commit()?;
    println!();

    let balance = wallet.get_balance();
    println!("Wallet balance after syncing: {} sats", balance.total());

    if balance.total() < SEND_AMOUNT {
        println!(
            "Please send at least {} sats to the receiving address",
            SEND_AMOUNT
        );
        std::process::exit(0);
    }

    let faucet_address = Address::from_str("mkHS9ne12qx9pS9VojpwU5xtRd4T7X7ZUt")?
        .require_network(Network::Testnet)?;

    let mut tx_builder = wallet.build_tx();
    tx_builder
        .add_recipient(faucet_address.script_pubkey(), SEND_AMOUNT)
        .enable_rbf();

    let mut psbt = tx_builder.finish()?;
    let finalized = wallet.sign(&mut psbt, SignOptions::default())?;
    assert!(finalized);

    let tx = psbt.extract_tx();
    client.broadcast(&tx)?;
    println!("Tx broadcasted! Txid: {}", tx.txid());

    Ok(())
}