README iterator

Iterator/README.md

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+# Iterator
+
+## Purpose
+
+To make an object iterable and to make it appear like a collection of objects.
+
+## Examples
+
+* to process a file line by line by just running over all lines (which have an object representation) for a file (which of course is an object, too)
+
+## Note
+
+Standard PHP Library (SPL) defines an interface Iterator which is best suited for this! Often you would want to implement the Countable interface too, to allow `count($object)` on your iterable object