[jQuery] How to select every checkbox on my page inside a fieldset

[ReynierPM]

Hi:
I have a fieldset and a set of check boxes inside. I want when I pick 
one, for example: <input type='checkbox' id='pick_all' 
value='picked_all' /> Pick all check boxes all the check boxes will be 
checked. How?
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Cheers
ReynierPM