Introduction

Extends the Array.prototype to have a method to check if there are any duplicate values in the array. Return true on the first duplicate found or false if no duplicates are found.

Example

```
require('npm-array-has-duplicate');

console.log([1, 3, 7, 11, 51].hasDuplicate());
console.log([1, 3, 7, 11, 51, 3].hasDuplicate());
```