Exercise : Unshift Challenge

unshift.md

Write a function that inserts an element at the begining of an array and returns the modified array.

Note: You cannot create a new array

CODE TEMPLATE

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let arr = [5,10,9];
function unshift(arr,newVal)
{
 // write your code here
}
console.log(unshift(arr,20)); // should print [20, 5,10, 9]

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