title: How to handle errors in GRequests?
body: <p>I have this code</p>
  
  <pre><code>#!/usr/bin/python
  
  import grequests
  
  urls = [
  'http://google.com',
  'http://doesnotexists.tld'
  ]
  
  
  def do_something(response, **kwargs):
          print response.text
  
  async_list = []
  
  for u in urls:
      action_item = grequests.get(u, timeout=10, hooks = {'response' : do_something})
      async_list.append(action_item)
  
  grequests.map(async_list,size=10)
  </code></pre>
  
  <p>How do I handle errors without getting usual Python error messages?<br>
  For example for domain which does not exists it prints out "not found".</p>