title: python3 type hints: arg: dict, passing a str type doesn't raise a Error
body: <p>the type of <code>cfg</code> should be <code>dict</code>.
  I pass a string of <code>str</code> type to <code>cfg</code>, there is no Error raised? why</p>
  
  <pre><code>def __to_oxml_json_p__(cfg: dict, content: list, panel_cfg: dict = None):
      print(type(cfg), cfg)
  </code></pre>
  
  <p>outputs:</p>
  
  <pre><code>&lt;class 'dict'&gt; {'size': '14 pt', 'bold': True, 'font_family': 'xxx'}
  &lt;class 'str'&gt; &lt;&lt;paragraph.basic&gt;&gt;
  </code></pre>
  
  <p>Why?</p>