title: loop in __init__ function?
body: <p>I am wondering if it is okay in style perspective to include for loop in <code>__init__</code> function of a class.</p>
  
  <p>Given a list of integers I am trying to generate <code>another_list</code> that stores differences in current value and next value. However I would like to use <code>another_list</code> for more than one method within the class. So I was thinking about creating another_list in <code>__init__</code> function rather than converting it for every method. Is this the most simplest way? what is the conventional style?</p>