title: How to get multiple values from Pandas dataframe whose indices and columns are known?
body: <p>I have a Pandas dataframe that looks like this</p>
  
  <pre><code>&gt;&gt; pd.DataFrame({'A': [1,2,3], 'B':[4,5,6], 'C':[7,8,9]})
  
       A   B   C  
  0    1   4   7  
  1    2   5   8  
  2    3   6   9  
  </code></pre>
  
  <p>I want to select values <code>1,6,8</code> that correspond to index-column pairs <code>(0,'A'),(2,'B'),(1,'C')</code>. How do I simultaneously select them?</p>