title: Matplotlib histogram title
body: <p>I'm trying to call a variable in a function of matplotlib, but it gives me an error. Maybe it's not possible. </p>
  
  <pre><code>sigma = float(some number)
  ax1.hist(population)
  ax1.set_title('blah   N = 241', 'standard deviation =',sigma)
  </code></pre>
  
  <p>It returns the error:</p>
  
  <pre><code>AttributeError: 'str' object has no attribute 'pop'  
  </code></pre>
  
  <p>or</p>
  
  <pre><code>AttributeError: 'int' object has no attribute 'pop'
  </code></pre>