docs: function dist() {
    process.env.NODE_ENV = 'production';
    return clean().then(() => {
      return Promise.all([
        compile({minify: true, checkTypes: false, isProdBuild: true}),
      ]).then(() => {
        // Push main "min" files to root to make them available to npm package.
        fs.copySync('./dist/activities.min.js', './activities.min.js');
        fs.copySync('./dist/activities.min.js.map', './activities.min.js.map');
        // Check types now.
        return compile({minify: true, checkTypes: true});
      }).then(() => {
        return rollupActivities('./index.js', 'activities.js');
      }).then(() => {
        return rollupActivities('./index-ports.js', 'activity-ports.js');
      }).then(() => {
        return rollupActivities('./index-hosts.js', 'activity-hosts.js');
      });
    });
  }