Convert multi dimension array to 1 dimension array

flattern.php

<?php
/**
 * Convert multi dimension array to 1 dimension array. Use this function when you need to convert 
 * wpdb results array to one dimension array
 *
 * @since 1.4.1
 * @return  string
 */
function flatten($v) {
	if(count($v, COUNT_RECURSIVE) !== count($v)) {
		$v = array_map('current', $v);
	}
	return $v;
}