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: show_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, ErrorKind, IsTerminal, Read};

use crate::cli;
use crate::config;
use crate::delta;
use crate::env::DeltaEnv;
use crate::git_config;
use crate::options::get::get_themes;
use crate::utils::bat::output::{OutputType, PagingMode};

pub fn show_themes(dark: bool, light: bool, computed_theme_is_light: bool) -> std::io::Result<()> {
    use std::io::BufReader;

    use bytelines::ByteLines;

    use super::sample_diff::DIFF;

    let env = DeltaEnv::default();
    let themes = get_themes(git_config::GitConfig::try_create(&env));
    if themes.is_empty() {
        return Err(std::io::Error::new(
            ErrorKind::NotFound,
            "No themes found. Please see https://dandavison.github.io/delta/cust
    
pub fn show_themes(dark: bool, light: bool, computed_theme_is_light: bool) -> std::io::Result<()> {
    use std::io::BufReader;

    use bytelines::ByteLines;

    use super::sample_diff::DIFF;

    let env = DeltaEnv::default();
    let themes = get_themes(git_config::GitConfig::try_create(&env));
    if themes.is_empty() {
        return Err(std::io::Error::new(
            ErrorKind::NotFound,
            "No themes found. Please see https://dandavison.github.io/delta/custom-themes.html.",
        ));
    }

    let mut input = DIFF.to_vec();

    if !io::stdin().is_terminal() {
        let mut buf = Vec::new();
        io::stdin().lock().read_to_end(&mut buf)?;
        if !buf.is_empty() {
            input = buf;
        }
    };

    let git_config = git_config::GitConfig::try_create(&env);
    let opt = cli::Opt::from_iter_and_git_config(
        env.clone(),
        &["delta", "--navigate", "--show-themes"],
        git_config,
    );
    let mut output_type =
        OutputType::from_mode(&env, PagingMode::Always, None, &config::Config::from(opt)).unwrap();
    let title_style = ansi_term::Style::new().bold();
    let writer = output_type.handle().unwrap();

    for theme in &themes {
        let git_config = git_config::GitConfig::try_create(&env);
        let opt = cli::Opt::from_iter_and_git_config(
            env.clone(),
            &["delta", "--features", theme],
            git_config,
        );
        let is_dark_theme = opt.dark;
        let is_light_theme = opt.light;
        let config = config::Config::from(opt);

        if (!computed_theme_is_light && is_dark_theme)
            || (computed_theme_is_light && is_light_theme)
            || (dark && light)
        {
            writeln!(writer, "\n\nTheme: {}\n", title_style.paint(theme))?;

            if let Err(error) =
                delta::delta(ByteLines::new(BufReader::new(&input[0..])), writer, &config)
            {
                match error.kind() {
                    ErrorKind::BrokenPipe => std::process::exit(0),
                    _ => eprintln!("{error}"),
                }
            }
        }
    }

    Ok(())
}