title: Matplotlib: set label font without setting label
body: <p>I would like to write a function that changes the font of all of the labels in a figure that I pass to it without actually changing the labels themselves.</p>
  
  <p>This is useful for figures that I have already created and need to have a uniform font style.</p>
  
  <p>Currently I am using multiple font dictionaries like so:</p>
  
  <pre><code>titleFont = {'family' : 'Arial',
               'weight' : 'bold',
               'size'   : 20}
  axesFont = {'family' : 'Arial',
               'weight' : 'bold',
               'size'   : 18}
  axesTickFont = {'family' : 'Arial',
                  'weight' : 'bold',
                  'size'   : 16}`
  </code></pre>
  
  <p>And then setting the font sizes by using commands along the lines of:</p>
  
  <pre><code>ax.set_title('My Plot',**titleFont)
  </code></pre>
  
  <p>The issue is that with the command above, I need to specify a plot title, when all I want to do is set the font style of an existing title.</p>
  
  <p>Something like this would be ideal:</p>
  
  <pre><code>def set_fonts(axis):
      axis.set_title(**titleFont)
      axis.set_ylabel(**axesFont)
      axis.set_xlabel(**axesFont)
      return axis
  </code></pre>