tor on the base iterators.  Generally this is satisfactory.
However, this implies that other operations (E. G. dereference) do not prematurely 
increment the base iterator.  Avoiding this can be surprisingly tricky in some cases.
(E.G. transform_width)

<p>
Iterators which fulfill the above requirements should be composable and the above sample
code should implement our binary to base64 conversion.

<h3>Iterators Included in the Library</h3>
Dataflow iterators for the serialization library are all defined i