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: main.rs
    path of file: ./repos/piano-trainer/src-tauri/src
    
    the code of the file until where you have to start completion: #![cfg_attr(
  all(not(debug_assertions), target_os = "windows"),
  windows_subsystem = "windows"
)]

use midir::{Ignore, MidiInput, MidiInputConnection};
use serde::Serialize;
use std::collections::HashMap;
use std::sync::{Arc, Mutex};
use tauri::{Manager, Window, Wry};
use tauri_plugin_store::PluginBuilder;

#[derive(Default)]
pub struct MidiState {
  pub input: Mutex<Option<MidiInputConnection<()>>>,
}

#[derive(Clone, Serialize)]
struct MidiMessage {
  message: Vec<u8>,
}

#[tauri::command]
fn list_m
    
fn list_midi_connections() -> HashMap<usize, String> {
  let midi_in = MidiInput::new("piano-trainer-input");
  match midi_in {
    Ok(midi_in) => {
      let mut midi_connections = HashMap::new();
      for (i, p) in midi_in.ports().iter().enumerate() {
        let port_name = midi_in.port_name(p);
        match port_name {
          Ok(port_name) => {
            midi_connections.insert(i, port_name);
          }
          Err(e) => {
            println!("Error getting port name: {}", e);
          }
        }
      }
      midi_connections
    }
    Err(_) => HashMap::new(),
  }
}