@property {function} can-observe/unshift unshift
@parent can-observe/array

@description Add elements to the start of an observe array.
@signature `list.unshift(...elements)`

  `unshift` adds elements onto the start of an observe array.

  ```js
  import { observe } from "can/everything";

  const names = new observe.Array(['Alice', 'Bob']);
  names.unshift('Chris');

  console.log(names); //-> ['Chris', 'Alice', 'Bob']
  ```
  @codepen

  @param {*} elements the elements to add to the Array

  @return {Number} the new length of the Array

@body

## Events

`unshift` causes _length_ events to be fired.