 If length is not given return the element at start, again assuming the array 
 is a circle.
 
+<code><pre>
+   [1, 2, 3].wrap(-1) 
+=> 3
+
+   [1, 2, 3].wrap(6) 
+=> 1
+
+   ["l", "o", "o", "p"].wrap(0, 16) 
+=> ["l", "o", "o", "p", "l", "o", "o", "p", "l", "o", "o", "p", "l", "o", "o", "p"]
+</pre></code>
+
 @name wrap
 @methodOf Array#
 

passed as in <code>each</each>.

<code><pre>
  results = []
  [1, 2, 3, 4].eachSlice 2, (slice) ->
    results.push(slice)
=> [1, 2, 3, 4]

  results
=> [[1, 2], [3, 4]] 
</pre></code>


Returns an object containing the extremes of this array.

<code><pre>
   [-1, 3, 0].extremes()
=> {min: -1, max: 3}
</pre></code>

