title: POST data encoding for request to Hackerrank API
body: <p>Hackerrank API documentation explains how send POST request to it.</p>
  
  <p>However, 'source' and 'testcases' parameters supposedly should be encoded, though I could not understand how exactly. I tried urencode (in PHP) on each of them and then building string with <code>=</code> and <code>&amp;</code> characters, but I get "400 bad request".</p>
  
  <p><strong>UPD</strong> Sorry for forgotten link to documentation page:
  <a href="http://www.hackerrank.com/api/docs" rel="nofollow">http://www.hackerrank.com/api/docs</a>
  third tab here shows sample with using curl.</p>