scripts/postinstall.js/setupAutocomplete
function setupAutocomplete() {
  return new Promise((resolve, reject) => {
    const indexRegex = new RegExp(path.join(path.sep, 'index.js'));
    const tabtabPath = require.resolve('tabtab').replace(indexRegex, '');
    const tabtabCliPath = path.join(tabtabPath, 'src', 'cli.js');

    try {
      execSync(`node ${tabtabCliPath} install --name serverless --auto`);
      execSync(`node ${tabtabCliPath} install --name sls --auto`);
      return resolve();
    } catch (error) {
      execSync(`node ${tabtabCliPath} install --name serverless --stdout`);
      execSync(`node ${tabtabCliPath} install --name sls --stdout`);
      console.log('Could not auto-install serverless autocomplete script.');
      console.log('Please copy / paste the script above into your shell.');
      return reject(error);
    }
  });
}