Add `isAssoc` to Collection class

IsAssocForCollectionServiceProvider.php

<?php

namespace App\Providers;

use Illuminate\Support\ServiceProvider;
use Illuminate\Support\Collection;
use Illuminate\Support\Arr;

class IsAssocForCollectionServiceProvider extends ServiceProvider
{
    public function boot()
    {
        // Result Arr::isAssoc
        Collection::macro('isAssoc', function() {
            if (!is_array($this->all（）)) {
                return false;
            }

            return Arr::isAssoc($this->all());
        });
    }
}