Merge pull request jbranchaud#4 from sdegutis/patch-1

Update mapping-with-an-index.md

Author: jbranchaud

clojure/mapping-with-an-index.md

@@ -9,3 +9,10 @@ can reach for `map-indexed`. The `map-indexed` function can be used like so:
 > (map-indexed (fn [idx item] (str idx " - " item)) foods)
 ("0 - pizza" "1 - hotdog" "2 - chicken alfredo")
 ```
+
+Alternatively, `map` can take multiple sequences, and each becomes a new argument to the mapping function. By giving an infinite sequential list of numbers starting at 0 as the first sequence, you can pretend they're indices, like so:
+
+```clojure
+> (map (fn [idx item] (str idx " - " item)) (range) foods)
+("0 - pizza" "1 - hotdog" "2 - chicken alfredo")
+```