public static function type($array)
	{
	    $last_key = -1;
	    $type = 'index';

	    foreach( $array as $key => $val )
	    {
	        if( !is_int( $key ) || $key < 0 )
	        {
	            return 'assoc';
	        }

	        if( $type !== 'sparse' ) 
	        {
		        if( $key !== $last_key + 1 ){
		            $type = 'sparse';
		        }
		        $last_key = $key;
		    }
	    }

	    return $type;
	}