ionicons not showing code example

Example: ion icons not wokring in ionic 3

import {Component} from 'angular2/core';
import {IONIC_DIRECTIVES} from 'ionic-angular';

@Component({
    selector: 'my-item',
    templateUrl: 'build/components/my-item/my-item.html',
    directives: [IONIC_DIRECTIVES]
})
export class MyItemComponent {
}