4.1: Collapse basic example
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**Primary Actor**: User

**Scope**: Ngx-bootstrap DEMO / BS version 3&4

**Goal**: Show user basic collapse functionality

Main success scenario:
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1. User opens Collapse demo page
2. User clicks on Basic sub-menu
3. User see clickable "Toggle collapse" button
4. User see div block with "Some content"
5. When user clicks on "Toggle collapse", then "Some content" disappear
6. When user clicks on "Toggle collapse" second time, then "Some content" appear

Variations:
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2*. User scrolls to Basic sub-menu