How to use the npmlog.levels function in npmlog

log.error("argv", process.argv.map(JSON.stringify).join(" "))
  log.error("node", process.version)
  log.error("npm ", "v" + npm.version)

  ; [ "file"
    , "path"
    , "code"
    , "errno"
    , "syscall"
    ].forEach(function (k) {
      var v = er[k]
      if (v) log.error(k, v)
    })

  // just a line break
  if (log.levels[log.level] <= log.levels.error) console.error("")

  switch (er.code) {
  case "ECONNREFUSED":
    log.error("", er)
    log.error("", ["\nIf you are behind a proxy, please make sure that the"
              ,"'proxy' config is set properly.  See: 'npm help config'"
              ].join("\n"))
    break

  case "EACCES":
  case "EPERM":
    log.error("", er)
    log.error("", ["\nPlease try running this command again as root/Administrator."
              ].join("\n"))
    break

function doBuild () {
    // Enable Verbose build
    var verbose = log.levels[log.level] <= log.levels.verbose
    var j

    if (!win && verbose) {
      argv.push('V=1')
    }

    if (win && !verbose) {
      argv.push('/clp:Verbosity=minimal')
    }

    if (win) {
      // Turn off the Microsoft logo on Windows
      argv.push('/nologo')
    }

    // Specify the build type, Release by default

function doBuild () {

    // Enable Verbose build
    var verbose = log.levels[log.level] <= log.levels.verbose
    if (!win && verbose) {
      argv.push('V=1')
    }
    if (win && !verbose) {
      argv.push('/clp:Verbosity=minimal')
    }

    if (win) {
      // Turn off the Microsoft logo on Windows
      argv.push('/nologo')
    }

    // Specify the build type, Release by default
    if (win) {
      var p = arch === 'x64' ? 'x64' : 'Win32'
      argv.push('/p:Configuration=' + buildType + ';Platform=' + p)

function doBuild () {

    // Enable Verbose build
    var verbose = log.levels[log.level] <= log.levels.verbose
    if (!win && verbose) {
      argv.push('V=1')
    }
    if (win && !verbose) {
      argv.push('/clp:Verbosity=minimal')
    }

    if (win) {
      // Turn off the Microsoft logo on Windows
      argv.push('/nologo')
    }

    // Specify the build type, Release by default
    if (win) {
      var p = arch === 'x64' ? 'x64' : 'Win32'
      argv.push('/p:Configuration=' + buildType + ';Platform=' + p)

function doBuild () {
    // Enable Verbose build
    var verbose = log.levels[log.level] <= log.levels.verbose
    var j

    if (!win && verbose) {
      argv.push('V=1')
    }

    if (win && !verbose) {
      argv.push('/clp:Verbosity=minimal')
    }

    if (win) {
      // Turn off the Microsoft logo on Windows
      argv.push('/nologo')
    }

    // Specify the build type, Release by default

var header = function(lvl, clientId, options) {
  if (npmlog.levels[npmlog.level] <= npmlog.levels[lvl]) {
    npmlog.log(lvl, clientId, HEADER_BANNER);
    npmlog.log(lvl, clientId, '| IBM MQ Light Node.js Client Module -',
               options.title);
    npmlog.log(lvl, clientId, HEADER_BANNER);
    npmlog.log(lvl, clientId, '| Date/Time         :-',
               moment().format('ddd MMMM DD YYYY HH:mm:ss.SSS Z'));
    npmlog.log(lvl, clientId, '| Host Name         :-', os.hostname());
    npmlog.log(lvl, clientId, '| Operating System  :-',
               os.type(), os.release());
    npmlog.log(lvl, clientId, '| Architecture      :-',
               os.platform(), os.arch());
    npmlog.log(lvl, clientId, '| Node Version      :-', process.version);
    npmlog.log(lvl, clientId, '| Node Path         :-', process.execPath);
    npmlog.log(lvl, clientId, '| Node Arguments    :-', process.execArgs);
    if (!isWin) {
      npmlog.log(lvl, clientId, '| User Id           :-', process.getuid());

var child_process =  require('child_process')
  , exec          =  child_process.exec
  , spawn         =  child_process.spawn
  , fs            =  require('fs')
  , path          =  require('path')
  , log           =  require('npmlog')
  , util          =  require('util')
  ;

log.level = log.levels.silly;

function execute (command, args, callback) {
  var errors  =  []
    , infos   =  []
    , spawned =  spawn (command, args)
    ;

  log.silly(command, args);

  spawned.stdout.on('data', function(data) {
    var msg = util.format('%s', data.toString());
    if (msg.length === 0) return;

    log.info(command, msg);
    infos.push(msg);
  });

logger.log = function(lvl, id, args) {
  if (npmlog.levels[npmlog.level] <= npmlog.levels[lvl]) {
    npmlog.log.apply(this, arguments);
  }
};

var _ = require('lodash')
var emoji = require('node-emoji')
var log = require('npmlog')

var levels = Object.keys(log.levels)

var exports = module.exports = _(log)

.pick(levels)
.value()

exports.levels = levels
exports.raw = log

log.style = {
  silly: {inverse: true, bold: true},
  verbose: {fg: 'brightBlue', bold: true},
  info: {fg: 'brightGreen', bold: true},
  http: {fg: 'brightGreen', bold: true},
  warn: {fg: 'brightYellow', bold: true},
  error: {fg: 'brightRed', bold: true},