title: how to get all possible combinations from array which contains all elements of another array
body: <p>I have an array containing unique numbers like <code>[2,3,4]</code>.
  I have another array which contains some numbers including duplicates like <code>a2 = [1,2,2,3,4,4,3,5,6,7]</code></p>
  
  <p>I want all possible combinations from array-2 which has all values of array-1
  like <code>[a2[1],a2[3],a2[4]]</code>,<code>[a2[2],a2[3],a2[4]]</code> etc.</p>