title: Finding index in list where the number begins to ascend
body: <p>say i have a list of numbers, i want to know where in the list do the numbers begin decreasing, in no particular order, an example would be ideal!</p>
  
  <pre><code>1,
  2,
  2,
  3,
  3,
  4,
  4,
  5,
  5,
  4, &lt;= this should be my output
  4,
  3,
  3,
  2,
  2,
  1,
  </code></pre>
  
  <p>thanks</p>