add statement 'alias' information to 'unshift' page

common-docs/reference/arrays/unshift.md

@@ -1,25 +1,43 @@
 # unshift
 
-Add an element to the front of an array.
+Add an element to the front of an array and return the new length of the array.
 
 ```sig
-[""].unshift("hello");
-[""]._unshiftStatement("hello");
+[""].unshift("hello")
+```
+Add an element to the front of an array but don't return the new length of the array.
+
+```sig
+[""]._unshiftStatement("hello")
 ```
 
 You might have an array with 3 numbers, like 1, 2, and 3. If you want to add another number to the front,
 then you _unshift_ it into the array. You do it like this:
 
 ```block
-let thoseNumbers = [1, 2, 3];
-let head = 0;
-head = thoseNumbers.unshift(0);
+let thoseNumbers = [1, 2, 3]
+let arrayLength = thoseNumbers.unshift(0)
 ```
 
 ## Parameters
 
 * **item**: the element to add to the front of the array.
 
+## Returns
+
+* the new length of the array.
+
+### ~reminder
+
+#### **shift** statement
+
+The ``||arrays:unshift||`` **statement** only adds an element to the front of the array. It doesn't the array length.
+
+```block
+["a", "b", "c"]._shiftStatement()
+```
+
+### ~
 ## Example
 
 Make an array that simulates a train. Place the parts of the train in the right order.
@@ -47,4 +65,4 @@ while (parts.length > 0) {
 
 ## Sea also
 
-[shift](/reference/arrays/shift), [push](/reference/arrays/push)
+[shift](/reference/arrays/shift), [push](/reference/arrays/push)