Function reader

crates/stdlib/src/csv.rs:368–387

(
        iter: PyIter,
        options: FormatOptions,
        // TODO: handle quote style, etc
        _rest: FuncArgs,
        vm: &VirtualMachine,
    )

    #[pyfunction]
    fn reader(
        iter: PyIter,
        options: FormatOptions,
        // TODO: handle quote style, etc
        _rest: FuncArgs,
        vm: &VirtualMachine,
    ) -> PyResult<Reader> {
        Ok(Reader {
            iter,
            state: PyMutex::new(ReadState {
                buffer: vec![0; 1024],
                output_ends: vec![0; 16],
                reader: options.to_reader(),
                skipinitialspace: options.get_skipinitialspace(),
                delimiter: options.get_delimiter(),
                line_num: 0,
            }),
            dialect: options.result(vm)?,
        })
    }

    #[pyfunction]
    fn writer(