Update README.md

Author: Smoren

README.md

@@ -24,7 +24,7 @@ composer test
 
 #### Range-based for (python-like)
 
-unlike the built-in function `range()`, `xrange()` does not create an array, but a generator 
+unlike the built-in function `range()`, `xrange()` does not create an array, but an `Traversable` object 
 that takes up a small amount of memory, regardless of the number of elements in the sequence.
 
 ```php