title: How to check if all values in a dataframe are True
body: <p><code>pd.DataFrame.all</code> and <code>pd.DataFrame.any</code> convert to <code>bool</code> all values and than assert all identities with the keyword <code>True</code>. This is ok as long as we are fine with the fact that non-empty lists and strings evaluate to True. However let assume that this is not the case.</p>
  
  <pre><code>&gt;&gt;&gt; pd.DataFrame([True, 'a']).all().item()
  True  # Wrong
  </code></pre>
  
  <p>A workaround is to assert equality with <code>True</code>, but a comparison to True does not sound pythonic.</p>
  
  <pre><code>&gt;&gt;&gt; (pd.DataFrame([True, 'a']) == True).all().item()
  False  # Right
  </code></pre>
  
  <p>Question: can we assert for identity with <code>True</code> without using <code>== True</code></p>