TeamCity Discord Bot

app.js

#!/usr/bin/env node
const Discord = require('discord.io');
const teamcity = require('teamcity');
const auth = require('../auth.json');

// Create Discord Bot
const bot = new Discord.Client({
  token: auth.token,
  autorun: true
});

// define some actions the bot will respond to
const actions = {
  ping: 'replies with pong',
  buildStatus: '!buildStatus {id} returns build status by Build ID'
};
// create TeamCity client connection
const tc = teamcity.create({
  url: 'https://your-tc-url.com',
  username: auth.tcuser,
  password: auth.tcpass
});

const getHelpMessage = () = {
  let msg = `**TCBot Usage**\n`;
  for (let key in actions) {
    msg += `\`${key}\`: ${actions[key]}\n`;
  }
  return msg;
}
// Send error message to console
bot.on('disconnect', (errMsg, code) => {
    console.log(errMsg, code);
});

bot.on('ready', evt => {
    console.info('Connected');
    console.info('Logged in as: ');
    console.info(bot.username + ' - (' + bot.id + ')');
});

bot.on('message', (user, userID, channelID, message, evt) => {
  // Configure the bot to listen for commands starting with !
  if (message.substring(0, 1) == '!') {
    let args = message.substring(1).split(' ');
    const cmd = args[0];
    args = args.splice(1);
    switch(cmd) {
      case 'help':
        bot.sendMessage({
            to: channelID,
            message: getHelpMessage()
        });
        break;
      case 'ping':
        bot.sendMessage({
            to: channelID,
            message: 'Pong!'
        });
        break;
      case 'buildStatus':
        let buildId = parseInt(args[0].replace(/[^\d.]/g, ''));
        tc.builds.get({ id: buildId }).then(res => {
          bot.sendMessage({
            to: channelID,
            message: '',
            embed: {
              color: 6826080,
              title: `Build Status ${res.status}`,
              fields: [
                {
                  name: 'Build Status',
                  value: `${res.status}`,
                  inline: true
                },
                {
                  name: 'Build State',
                  value: `${res.state}`,
                  inline: true
                },
                {
                  name: 'Status Text',
                  value: `\`\`\`${build.statusText}\`\`\``,
                  inline: false
                }
              ]
            }
          });
        });
        break;
    }
  }
});

auth.json

{
   "token": "YOUR-BOTS-TOKEN",
   "tcuser": "a-tc-user",
   "tcpass": "pass-for-user"
}

Hello, what does this line: const teamcity = require('teamcity'); requires?
Is it a node module?