Function to_csv_writer 

pub fn to_csv_writer<W: Write>(doc: &Document, writer: W) -> Result<()>

Write a HEDL document to CSV format using a writer.

Example

use hedl_core::Document;
use hedl_csv::to_csv_writer;
use std::fs::File;

let doc = Document::new((1, 0));
let file = File::create("output.csv").unwrap();
to_csv_writer(&doc, file).unwrap();