title: Get response headers from Curb
body: <p>I intend to make a call from a Ruby on Rails application:</p>
  
  <pre><code>c = Curl::Easy.http_post("https://example.com", json_string_goes_here) do |curl|
    curl.headers['Accept'] = 'application/json'
    curl.headers['Content-Type'] = 'application/json'
    curl.headers['Api-Version'] = '2.2'
  end
  </code></pre>
  
  <p>The response should have custom headers:</p>
  
  <pre><code>X-Custom1 : "some value"
  X-Custom2 : "another value"
  </code></pre>
  
  <p>How do I iterate over the response headers to compare the values to what I was expecting?</p>