src/Client.php
private function normalRandom($size)
    {
        $id = '';
        while (1 <= $size--) {
            $rand = mt_rand()/(mt_getrandmax() + 1);
            $id .= $this->alphbet[$rand*64 | 0];
        }

        return $id;
    }
private function normalRandom($size)
    {
        $id = '';
        while (1 <= $size--) {
            $rand = mt_rand()/(mt_getrandmax() + 1);
            $id .= $this->alphbet[$rand*64 | 0];
        }

        return $id;
    }
Generate secure URL-friendly unique ID.
By default, ID will have 21 symbols to have same collisions probability
as UUID v4.

@see https://github.com/ai/nanoid/blob/master/index.js
@param integer $size
@return string