title: Extracting values for a specific key from a list of dicts
body: <p>I would like to extract specific values from a JSON object to a dedicated list. My code looks like that:</p>
  
  <pre><code>url2 = 'https://pqrsiem/api/reference_data/sets/clearsky_DOMAIN?fields=data(first_seen)'
  request = urllib2.Request(url2,headers=headers)
  response = urllib2.urlopen(request)    
  parsed_response = json.loads(response.read().decode('utf-8'))
  print(json.dumps(parsed_response, indent=4))
  </code></pre>
  
  <p>The output looks like this:</p>
  
  <pre><code>{"data": [
      {
          "first_seen": 1474468912626
      }, 
      {
          "first_seen": 1474468912694
      }, 
      {
          "first_seen": 1474468912762
      }, 
      ...
      ]
  }
  </code></pre>
  
  <p>I would like to extract the values from the <code>"first_seen"</code> key and put them in a list.
  How can I do it?</p>