2.6: Buttons Uncheckable Radio example
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**Primary Actor**: User

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

**Goal**: Show user uncheckable radio buttons example

Main success scenario:
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1. User opens Buttons demo page
2. User clicks on Uncheckable Radio sub-menu
3. User see button-group, which contain of 3 parts(labels)
4. By default, in each group, 1st button is inactive, 2d - active and 3d - inactive
5. User able to click on each button
6. When user clicks on the active button, it become inactive and other buttons stay inactive (and there is "Null" message in this demo block)
7. When 1 button is active, other is inactive.

Variations:
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2*. User scrolls to Uncheckable Radio sub-menu
