title: validate yaml file with dynaconf or schema in python
body: <p>I have a fairly yaml file corresponding to nested dict, which I want to validate with dynaconf. I'm following the guide here: <a href="https://www.dynaconf.com/validation/" rel="nofollow noreferrer">https://www.dynaconf.com/validation/</a>  but their example is pretty simple, and I can't find a way to validate data which corresponds to nested dictionaries, like in my example below:</p>
  <pre><code>---
  item1:
      - prod1: val1
      - prod2
          - proda: vala
          - prodb: |
              valb1
              valb2
  version: 1
  ---
  item2:
      prodx: valx
  </code></pre>
  <p>For instance I would like to make sure that vala, valb2, valx all should exist.</p>
  <pre><code>settings = Dynaconf(
      settings_files=['file.yml'],
      validators=[
          Validator(&quot;proda&quot;, must_exist=True, eq='vala'),
          Validator(&quot;version&quot;, must_exist=True, is_type_of=int),
          ...
      ]
  </code></pre>
  <p>Or, if you know something else, like &quot;schema&quot; library, which could be more suitable for this job let me know.
  p.s. I also want to keep multiple yaml configs in one file, separated by ---</p>