How to use the just-task.task function in just-task

condition('jest', () => !argv().min),
      series(
        argv().commonjs ? 'ts:commonjs-only' : 'ts',
        condition('lint-imports', () => !argv().min),
        parallel(condition('webpack', () => !argv().min), condition('verify-api-extractor', () => !argv().min))
      )
    )
  )
);

// Special case build for the serializer, which needs to absolutely run typescript and jest serially.
task('build-jest-serializer-merge-styles', series('ts', 'jest'));

task('build-commonjs-only', series('clean', 'ts:commonjs-only'));
task('code-style', series('prettier', 'tslint'));
task('update-api', series('clean', 'copy', 'sass', 'ts', 'update-api-extractor'));
task('dev', series('clean', 'copy', 'sass', 'webpack-dev-server'));

// Utility functions

function getPackage() {
  if (packageJson) {
    return packageJson;
  }

  let packagePath = path.resolve(process.cwd(), 'package.json');

  if (fs.existsSync(packagePath)) {
    packageJson = JSON.parse(fs.readFileSync(packagePath, 'utf8'));
    return packageJson;
  }

// @ts-check

const { task, parallel } = require('just-task');
const { tscTask, copyTask, jestTask, outdatedTask, selfUpdateTask } = require('../lib/index');

//task('build', parallel(tscTask(), tscTask()));
task('ts', tscTask({}));

task(
  'build',
  parallel(() => {
    return copyTask([], '');
  })
);

task('test', jestTask());
task('start-test', jestTask({ watch: true }));

const spec = {
  versionSpec: {
    'just-task': 'latest',
    'office-ui-fabric-react': '>=6.0.0 <7.0.0'
  }

// @ts-check

const path = require('path');
const { task, series, condition, option, argv } = require('just-task');
const { tscTask, tslintTask, cleanTask } = require('just-scripts');
const libPath = path.resolve(process.cwd(), 'lib');
const srcPath = path.resolve(process.cwd(), 'src');

if (require('fs').existsSync(path.resolve(__dirname, '../../../scripts/just-task.js'))) {
  require('../../../scripts/just-task')
} else {

  option('production');
  option('clean');

  task('tslint', () => {
    return tslintTask();
  });
  task('ts', () => {
    return tscTask({
      pretty: true,
      ...(argv().production && { inlineSources: true, sourceRoot: path.relative(libPath, srcPath) }),
      target: 'es5',
      outDir: 'lib',
      module: 'commonjs',
    });
  });
  task('clean', () => {
    return cleanTask(['lib', 'temp', 'dist', 'coverage'].map(p => path.join(process.cwd(), p)));
  });

  task(

const download = require('./scripts/download')
const cleanup = require('./scripts/cleanup')
const {getArgvFromNpmEnv, getArgvFromPkgJson} = require('./scripts/npm_argv')

option('electron_version', {default: '5.0.8'});
option('runtime', {default: 'electron', choices: ['electron', 'node']});
option('platform', {default: process.platform, choices: ['darwin', 'win32']});
// option('packageVersion');
option('debug', {default: false, boolean: true});
option('silent', {default: false, boolean: true});
option('msvs_version', {default: '2015'});

const packageVersion = require('./package.json').version;

// npm run build:electron -- 
task('build:electron', () => {
  build({
    electronVersion: argv().electron_version, 
    runtime: argv().runtime, 
    platform: argv().platform, 
    packageVersion, 
    debug: argv().debug, 
    silent: argv().silent,
    msvsVersion: argv().msvs_version
  })
})
// npm run build:node --
task('build:node', () => {
  build({
    electronVersion: argv().electron_version, 
    runtime: 'node',
    packageVersion,

export function lib() {
  task('clean', cleanTask([...defaultCleanPaths(), 'lib-commonjs']));

  task('ts:commonjs', tscTask({ module: 'commonjs', outDir: 'lib-commonjs' }));
  task('ts:esm', tscTask({ module: 'esnext', outDir: 'lib' }));
  task('ts:watch', tscTask({ module: 'esnext', outDir: 'lib', watch: true }));
  task('ts', parallel('ts:commonjs', 'ts:esm'));

  task('jest', jestTask());
  task('jest:watch', jestTask({ watch: true }));

  task('tslint', tslintTask());

  task('build', series('ts'));
  task('test', series('jest'));
  task('lint', series('tslint'));

  task('start', series('clean', 'ts:watch'));
  task('start-test', series('jest:watch'));

  task('rebuild', series('clean', 'build'));
}

export function webapp() {
  task('clean', cleanTask([...defaultCleanPaths(), 'lib-commonjs']));

  task('ts:esm', tscTask({ module: 'esnext', outDir: 'lib' }));
  task('ts:watch', tscTask({ module: 'esnext', outDir: 'lib', watch: true }));
  task('ts', parallel('ts:esm'));

  task('jest', jestTask());
  task('jest:watch', jestTask({ watch: true }));

  task('tslint', tslintTask());

  task('webpack', webpackTask());

  task('webpack:watch', webpackDevServerTask());

  task('build', series('ts', 'webpack'));
  task('test', series('jest'));
  task('start', series('webpack:watch'));
  task('start-test', series('jest:watch'));

export function monorepo() {
  option('cwd');
  option('name', { alias: 'n' });
  option('stack', { alias: 's' });
  option('latest');
  task('add-package', 'adds a package to the monorepo', addPackageTask);
  task('upgrade-repo', 'upgrades packages inside the monorepo according to the just-stack template', upgradeRepoTask);
}

export function lib() {
  task('clean', cleanTask([...defaultCleanPaths(), 'lib-commonjs']));

  task('ts:commonjs', tscTask({ module: 'commonjs', outDir: 'lib-commonjs' }));
  task('ts:esm', tscTask({ module: 'esnext', outDir: 'lib' }));
  task('ts:watch', tscTask({ module: 'esnext', outDir: 'lib', watch: true }));
  task('ts', parallel('ts:commonjs', 'ts:esm'));

  task('jest', jestTask());
  task('jest:watch', jestTask({ watch: true }));

  task('tslint', tslintTask());

  task('build', series('ts'));
  task('test', series('jest'));
  task('lint', series('tslint'));

  task('start', series('clean', 'ts:watch'));
  task('start-test', series('jest:watch'));

  task('rebuild', series('clean', 'build'));
}

export function monorepo() {
  option('cwd');
  option('name', { alias: 'n' });
  option('stack', { alias: 's' });
  option('latest');
  task('add-package', 'adds a package to the monorepo', addPackageTask);
  task('upgrade-repo', 'upgrades packages inside the monorepo according to the just-stack template', upgradeRepoTask);
}