title: Optional argument for the graph title to allow overriding the currently generated title
body: <p>Answer is in the following, which was suggested by a welcomed viewer.
  <a href="https://stackoverflow.com/questions/15301147/python-argparse-default-value-or-specified-value">Python argparse: default value or specified value</a></p>
  
  <p>I need help with overwriting my title from the shell when I run the python program. So far, I just hard code the name inside of the program as below. But, I need an option called <code>-title</code> which should follow with the new title. It should be an optional option, so if no <code>-title</code> when running the program, the current title should stay the same. Example would be like:</p>
  
  <p><code>&gt;python Graph.py -title "New Title"</code></p>
  
  <p>This should overwrite the old title with the new one.
  But if I type just</p>
  
  <p><code>&gt;python Graph.py</code></p>
  
  <p>It should keep the title as "Old Title".</p>
  
  <p>I surfed the internet and found that I need argument with parser or string. I think using string with argument would work but I am not sure how to make the option optional, so if there is not -title, the title should stay the same.</p>
  
  <p>Right now, I have the following hard coded </p>
  
  <p><code>plt.title("\n".join(wrap("Performance for "+file1+' &amp; '+file2 +' &amp; '+file3)), size = 12)</code></p>