title: How to use list comprehension with .extend list method?
body: <p>For example, this snippet:</p>
  
  <pre><code>out = []
  for foo in foo_list:
      out.extend(get_bar_list(foo)) # get_bar_list return list with some data
  return out
  </code></pre>
  
  <p>How to shorten this code using <strong>list comprehension</strong>?</p>