title: Diff two yaml files using python
body: <p>How can I do diff of two YAML files and generate base on this comparison new file?
  For example:</p>
  <pre><code>users:
  - login: user1
    first_name: MyUser1
    last_name: MyUser1
    groups:
      - admin
      - db
      - hr
  - login: user2
    first_name: MyUser2
    last_name: MyUser2
    groups:
      - admin
      - hr
  </code></pre>
  <p>and second version of file (removed group admin):</p>
  <pre><code>users:
  - login: user1
    first_name: MyUser1
    last_name: MyUser1
    groups:
      - db
      - hr
  - login: user2
    first_name: MyUser2
    last_name: MyUser2
    groups:
      - admin
      - hr
  </code></pre>
  <p>and get something like(with only difference):</p>
  <pre><code>users:
  - login: user1
    groups:
      - admin
  </code></pre>
  <p>If someone will remove full section for example user1 so:</p>
  <pre><code>users:
  - login: user2
    first_name: MyUser2
    last_name: MyUser2
    groups:
      - admin
      - hr
  </code></pre>
  <p>i need to only have result like:</p>
  <pre><code>removed_users:
    user1 
  </code></pre>
  <p>or simply nothing the most important is when group for user is removed</p>