0.9: Accordion Open only one at a time example
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**Primary Actor**: User

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

**Goal**: Show user on a time accordion functionality (open only 1 item at a time)

Main success scenario:
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1. User open Accordion demo page
2. User click on Open only one at a time sub-menu
3. User able to click on each item of 3
4. User see checked check-box "Open only one at a time" by default
5. When user click on 1st item, it opened
6. When user click on 2d item, it opened and 1st is closed
7. When user click on 3d item, it opened and 2d is closed
8. When user uncheck the check-box "Open only one at a time"
9. Then after click on each item, it stays opened.

Variations:
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2*. User scroll to Open only one at a time sub-menu