title: How to query pandas dataframe using a specific value?
body: <p>I have pandas dataframe with the following contents:</p>
  
  <pre><code>    A   B     C  D
  0 red, t1, blue, 1
  1 red, t1, yellow, 2
  2 red, t0, green, 1
  3 red, t0, blue, 1
  4 red, t0, blue, 2
  5 green, t1, yeallow, 1
  6 green, t0, red, 1
  7 green, t0, yellow, 1
  8 blue, t0, yellow, 1
  9 blue, t1, red, 1
  10 yellow, t1, red, 3
  </code></pre>
  
  <p>How to extract all the rows that for <code>A</code> equal to <code>'green'</code> AND for <code>B</code> equal to <code>t0</code> for example?</p>