demo/src/app/components/+collapse/demos/basic/basic.html
<button type="button" class="btn btn-primary" (click)="isCollapsed = !isCollapsed"
[attr.aria-expanded]="!isCollapsed" aria-controls="collapseBasic">Toggle collapse
</button>
<hr>
<div id="collapseBasic" [collapse]="isCollapsed" class="card card-block card-header">
<div class="well well-lg">Some content</div>
</div>