title: Count occurences of True/False in column of dataframe
body: <p>Is there a way to count the number of occurrences of boolean values in a column without having to loop through the DataFrame?</p>
  
  <p>Doing something like </p>
  
  <pre><code>df[df["boolean_column"]==False]["boolean_column"].sum()
  </code></pre>
  
  <p>Will not work because False has a value of 0, hence a sum of zeroes will always return 0.</p>
  
  <p>Obviously you could count the occurrences by looping over the column and checking, but I wanted to know if there's a pythonic way of doing this.</p>