jashkenas/underscore — pull request #1271 by sol0mka (2013-08-23 07:50:09+00:00)
Title: add toggle array function

Toggle item in array function was really useful for me many times.

Toggle item in array. If array contains many such items, they will
be removed entirely. If you pass optional isSingle then only first one of them
will be removed.

One of the usecases:
http://codepen.io/sol0mka/pen/kedaw
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