Interval calculation in Python : <p>I am writing a program where I need to calculate the total watch time of a movie.</p>

<pre><code>1st watch = (0,10)
2nd Watch =(13,18)
3rd watch =(15,23)
4th watch =(21,26)
</code></pre>

<p>Total movie watched=10+5+5+3=23 min</p>

<p>How can I implement this in Python</p>
