How remember_token is generated by laravel automatically? Can we do the same in codeigniter?

I am new in MVC. Can anyone tell me where the function for remember_token is written in laravel? I saw in Bluprint and found this function:

    public function rememberToken()
{
    return $this->string('remember_token', 100)->nullable();
}

which is just a function to define a field in database. I also saw in Contracts/Auth/Authenticable.php but here also i found a bunch of interfaces defined along with the getremembertoken and setremembertoken as:

      interface Authenticatable
       {
      public function getRememberToken();
      public function setRememberToken($value);
      public function getRememberTokenName();
    }

Where is the actual function written for generating token that is saved in database? Can anyone tell me please? And can I implement the similar function in codeigniter?

via Chebli Mohamed