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: usb_serial_with_logger.rs
    path of file: ./repos/embassy/examples/rp/src/bin
    
    the code of the file until where you have to start completion: //! This example shows how to use USB (Universal Serial Bus) in the RP2040 chip as well as how to create multiple usb classes for one device
//!
//! This creates a USB serial port that echos. It will also print out logging informa
    
async fn echo<'d, T: Instance + 'd>(class: &mut CdcAcmClass<'d, Driver<'d, T>>) -> Result<(), Disconnected> {
    let mut buf = [0; 64];
    loop {
        let n = class.read_packet(&mut buf).await?;
        let data = &buf[..n];
        info!("data: {:x}", data);
        class.write_packet(data).await?;
    }
}