ode> functions.</p>
  
   <p>Iterators are evaluated using the <code>next/1</code> function to evaluate   
the next element of the iterator. The output of the next function   
is a lazy list: either an improper list of the element and the   
continuation or an empty list. Many additional iterator   
transformation and evaluation functions are also present.</p>
  
   <p>In general, iterators are not expected to be pure functions.   
Iterator transformations and evaluations should all evaluate each   
element