title: Dataframe test two conditions
body: <p>For this dataframe
  df</p>
  
  <pre><code>   basketID  productCode
  0         1           23
  1         1           24
  2         1           25
  3         2           23
  4         3           23
  5         4           25
  6         5           24
  7         5           25
  </code></pre>
  
  <p>Gives as expected</p>
  
  <pre><code>(df['productCode']) == 23
  0     True
  1    False
  2    False
  3     True
  4     True
  5    False
  6    False
  7    False
  </code></pre>
  
  <p>But if I want both 23 and 1</p>
  
  <pre><code>(df['productCode']) == 23 &amp; (df['basketID'] == 1)
  0    False
  1    False
  2    False
  3    False
  4    False
  5    False
  6    False
  7    False
  </code></pre>
  
  <p>Everything is false.
  Why first line was not recognized?</p>