title: Changing attributes of a button in python
body: <p>After I have created a button or any other object as such, how can I change its properties later on in the code?
  For example: </p>
  
  <pre><code>b = Button(root, text="button")
  </code></pre>
  
  <p>How do I change the text in <code>b</code> or add a command for <code>b</code>.
  I actually want to change the colour of <code>b</code> when it is clicked.</p>