title: Update list in dictionary if key not present in list
body: <p>I am trying to find the best approach to update the values of the dictionary including the key when this (key) is not present in the value.</p>
  <p>I proceeded as follows:</p>
  <pre><code>        for key, value in m_dict.items():
              if key not in value:
                  m_list = m_dict.get(key)
                  m_list.append(key)
                  m_dict[key] = m_list
  </code></pre>
  <p>That works, but I can see it is a bit lengthy. Can I update the values including they key when this is not present in a better way?</p>
  <p>Thanks for sharing</p>