title: Grouping a sequence of numbers with no gaps in javascript using underscore.js
body: <p>Having an array of numbers <code>[1, 2, 3, 4, 7, 8, 11, 15, 16, 17, 18]</code>, how can we group them in groups of consecutive numbers using underscore.js. </p>
  
  <p>So the desired output is 4 groups (1-4, 7-8, 11 and 15-18)
  <code>[[1, 2, 3, 4], [7, 8], [11], [15, 16, 17, 18]]</code></p>