<p><strong>At the risk of repeating myself</strong>
we need to learn how to run code repeatedly.  There are two forms of looping
in Python, definite and indefinite.  We will do definite looping
first.</p>

<p><strong>What is an iterator?</strong> An iterator is a rule that governs
the manner in which a collection is traversed.  If an object has an iterator,
it is called an <em>iterable</em>.  All Python container types
are iterables, as we shall soon see.</p>

<p><strong>Home on the <code>range</code></strong>   This is an iterator
that walks through an arithmetic integer sequence.</p>

<p>find all scrabble words taht contain 3 or more Z, and 
print them out.</p>