title: GuzzleHTTP how to get Request Header
body: <p>I want to print out the request header of a POST request, but I can't find the answer by searching the web. Can someone explain how to do this?</p>
  
  <p>I have this array that I pass in the POST request as $value. I want to see how it's parsed in the GuzzleHTTP POST request.</p>
  
  <p>Array example</p>
  
  <pre><code>Array
  (
      [username] =&gt; admin
  
      [password] =&gt; pass
  
      [submit] =&gt; login
  
  )
  
  $client-&gt;request('POST', $url, [
                              'form_params' =&gt; [
                                  $value
                              ]
                          ]);
  </code></pre>