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: hello_world.rs
    path of file: ./repos/avrow/examples
    
    the code of the file until where you have to start completion: // A hello world example of reading and writing avro data files

use anyhow::Error;
use avrow::from_value;
use avrow::Reader;
use avrow::Schema;
use avrow::Writer;
use std::str::FromStr;

use std::io::Cursor;

fn main() -> Result<(), Error> {
    // Writing data

    // Create a schema
    let schema = Schema::from_str(r##""null""##)?;
    // Create writer using schema and provide a buffer (implements Read) to write to
    let mut writer = Writer::new(&schema, vec![])?;
    // Write the data using write and creating a Value manually.
    writer.write(())?;
    // or the more convenient and intuitive serialize method that takes native Rust types.
    writer.serialize(())?;
    // retrieve the underlying buffer using the buffer method.
    
fn main() -> Result<(), Error> {
    // Writing data

    // Create a schema
    let schema = Schema::from_str(r##""null""##)?;
    // Create writer using schema and provide a buffer (implements Read) to write to
    let mut writer = Writer::new(&schema, vec![])?;
    // Write the data using write and creating a Value manually.
    writer.write(())?;
    // or the more convenient and intuitive serialize method that takes native Rust types.
    writer.serialize(())?;
    // retrieve the underlying buffer using the buffer method.
    // TODO buffer is not intuive when using a file. into_inner is much better here.
    let buf = writer.into_inner()?;

    // Reading data

    // Create Reader by providing a Read wrapped version of `buf`
    let reader = Reader::new(Cursor::new(buf))?;
    // Use iterator for reading data in an idiomatic manner.
    for i in reader {
        // reading values can fail due to decoding errors, so the return value of iterator is a Option<Result<Value>>
        // it allows one to examine the failure reason on the underlying avro reader.
        dbg!(&i);
        // This value can be converted to a native Rust type using `from_value` method that uses serde underneath.
        let _val: () = from_value(&i)?;
    }

    Ok(())
}