How to use the azk._.isEmpty function in azk

getSystemsByName(names) {
    var systems_name = this.systemsInOrder();

    if (!_.isEmpty(names)) {
      names = _.isArray(names) ? names : names.split(',');
      _.each(names, (name) => this.system(name, true));
      systems_name = _.intersection(systems_name, names);
    }

    return _.reduce(systems_name, (systems, name) => {
      systems.push(this.system(name, true));
      return systems;
    }, []);
  }

__show_examples() {
    if (!_.isEmpty(this.examples)) {
      this.output();
      this.tOutput("commands.help.examples");
      this.output();
      _.each(this.examples, (example) => {
        this.output(`  ${example}`);
      });
    }
  }

unwatch() {
    if (!_.isEmpty(this.chok)) {
      this._send('sync', 'close');
      this.chok.close();
      this.chok = null;
    }
  }

static _deprecate(value, manifest, system, option, new_option) {
    if (!_.isEmpty(value)) {
      return [
        this._entry('deprecate', 'deprecated', manifest, { system, option, new_option })
      ];
    }
    return [];
  }