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: crate_versions.rs
    path of file: ./repos/vector/vdev/src/commands
    
    the code of the file until where you have to start completion: use std::{collections::HashMap, collections::HashSet, process::Command};

use anyhow::Result;
use clap::Args;
use itertools::Itertools as _;
use regex::Regex;

use crate::{app::CommandExt as _, util};

/// Show information about crates versions pulled in by all dependencies
#[derive(Args, Debug)]
#[command()]
pub struct Cli {
    /// Show all versions, not just those that are duplicated
    #[arg(long)]
    a
    
    pub fn exec(self) -> Result<()> {
        let re_crate = Regex::new(r" (\S+) v([0-9.]+)").unwrap();
        let mut versions: HashMap<String, HashSet<String>> = HashMap::default();

        for line in Command::new("cargo")
            .arg("tree")
            .features(&self.feature)
            .check_output()?
            .lines()
        {
            if let Some(captures) = re_crate.captures(line) {
                let package = &captures[1];
                let version = &captures[2];
                versions
                    .entry(package.into())
                    .or_default()
                    .insert(version.into());
            }
        }

        if !self.all {
            versions.retain(|_, versions| versions.len() > 1);
        }

        let width = versions.keys().map(String::len).max().unwrap_or(0).max(7);
        if *util::IS_A_TTY {
            println!("{:width$}  Version(s)", "Package");
            println!("{:width$}  ----------", "-------");
        }

        for (package, versions) in versions {
            let versions = versions.iter().join(" ");
            println!("{package:width$}  {versions}");
        }

        Ok(())
    }