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: list_syntax_themes.rs
    path of file: ./repos/delta/src/subcommands
    
    the code of the file until where you have to start completion: use std::io::{self, IsTerminal, Write};

use itertools::Itertools;

use crate::{options::theme::is_light_syntax_theme, utils};

#[cfg(not(tarpaulin_include))]
pub fn list_syntax_themes() -> std::io::Result<()> {
    let stdout = io::stdout();
    let mut stdout = stdout.lock();
    if stdout.is_terminal() {
        _list_syntax_themes_for_humans(&mut stdout)
    } else {
        _list_syntax_themes_for_machines(&mut stdout)
    }
}

pub fn _list_syntax_themes_for_humans(writer: 
    
pub fn _list_syntax_themes_for_humans(writer: &mut dyn Write) -> std::io::Result<()> {
    let assets = utils::bat::assets::load_highlighting_assets();

    writeln!(writer, "Light syntax themes:")?;
    for theme in assets.themes().filter(|t| is_light_syntax_theme(t)) {
        writeln!(writer, "    {theme}")?;
    }
    writeln!(writer, "\nDark syntax themes:")?;
    for theme in assets.themes().filter(|t| !is_light_syntax_theme(t)) {
        writeln!(writer, "    {theme}")?;
    }
    writeln!(
        writer,
        "\nUse delta --show-syntax-themes to demo the themes."
    )?;
    Ok(())
}