Add example for uint::range_step.

src/libstd/num/uint_macros.rs

@@ -64,9 +64,18 @@ pub fn ge(x: $T, y: $T) -> bool { x >= y }
 pub fn gt(x: $T, y: $T) -> bool { x > y }
 
 #[inline(always)]
-///
-/// Iterate over the range [`start`,`start`+`step`..`stop`)
-///
+/**
+ * Iterate through a range with a given step value.
+ *
+ * # Examples
+ * ~~~ {.rust}
+ * let nums = [1,2,3,4,5,6,7];
+ *
+ * for uint::range_step(0, nums.len() - 1, 2) |i| {
+ *     println(fmt!("%d & %d", nums[i], nums[i+1]));
+ * }
+ * ~~~
+ */
 pub fn range_step(start: $T, stop: $T, step: $T_SIGNED, it: &fn($T) -> bool) -> bool {
     let mut i = start;
     if step == 0 {