Varint is represented as num_bigint::BigInt

fn main() {
extern crate scylla;
extern crate num_bigint;
use scylla::Session;
use std::error::Error;
async fn check_only_compiles(session: &Session) -> Result<(), Box<dyn Error>> {
use scylla::IntoTypedRows;
use num_bigint::BigInt;
use std::str::FromStr;

// Insert a varint into the table
let to_insert: BigInt = BigInt::from_str("12345")?;
    .query("INSERT INTO keyspace.table (a) VALUES(?)", (to_insert,))

// Read a varint from the table
if let Some(rows) = session.query("SELECT a FROM keyspace.table", &[]).await?.rows {
    for row in rows.into_typed::<(BigInt,)>() {
        let (varint_value,): (BigInt,) = row?;