Adds note about iterators having same signature as procs.

doc/tut1.txt

@@ -813,7 +813,11 @@ important differences:
 
 However, you can also use a ``closure`` iterator to get a different set of
 restrictions. See `first class iterators <manual.html#first-class-iterators>`_
-for details.
+for details. Iterators can have the same name and parameters as a proc,
+essentially they have their own namespace. Therefore it is common practice to
+wrap iterators in procs of the same name which accumulate the result of the
+iterator and return it as a sequence, like ``split`` from the `strutils module
+<strutils.html>`_.
 
 
 Basic types