title: Array value comparison with a multidimension array ruby
body: <p>If i have 2 arrays like let's say :</p>
  <pre><code>arr1 = [1,2,3,4,5,6]
  arr2 = [[2,4],12]
  </code></pre>
  <p>i would like to return variable  :</p>
  <pre><code>result=[1,3]
  </code></pre>
  <p>How can i create a variable that returns the indexes from arr1 that corresponds to the values from the arr2 nested array.</p>